Menu Close

Biology overview Andrew douch overview

Question Answer
Differences between plant and animal cells Plant cells have a cell wall…. Plant cells have a large vacuole wheres…. Animal cells have centriole…. Chrloroplasts are found in some plant cells but no animal cells.
Plasma membrane The plasma membrane is composed of a bilayer of phospholipids with various proteins suspended in it. Many of these proteins are involved in cell-cell communication . Others are involved in the movement of material via active transport of facilitated
Osmosis The net passive movement of free water molecules from a region with low (solute) concentration to a region with relatively high concentration, through a permeable membrane
Simple diffusion The net passive movement of a molecule from a region with a high concentration to a region with a relatively low concentration
Facilitated diffusion The passive movement of a molecule through a membrane, down a concentration gradient, via either a channel protein from one side of a membrane to the other.
Bulk transport The movement of molecules or other items too large to pass through a membrane by the enveloping of the item within a membrane sac formed from a pinching off of the plasma membrane.
Bulk transport (Endocytosis) If the item is moved from outside the cell to inside, bulk transport is referred to as endocytosis
Bulk transport (Exocytosis) If the item is moved out of the cell it is called exocytosis
Types of molecules Small ions…. Small polar molecules…. Small non-polar molecules…. Large polar molecules…. Large non-polar molecules
How small ions move across a membrane Small ions will have trouble passing through a membrane because of their electrical charge which is repelled from the non-polar interior of the phospholipid bilayer. eg( sodium Na+)
How small polar molecules move across a membrane Small polar molecules are also repelled by the interior of the membrane, but not as strongly. Therefore, very small polar molecules can cross the membrane, although with difficulty. (water)
How small non-polar molecules move across a membrane Small non-polar molecules such as carbon dioxide and oxygen gas, are not repelled by the fatty acid interior of the membrane, and are therefore able to diffuse readily across the membrane, darting between the gaps of the phospholipid bilayer
How large polar molecules move across a membrane Large polar molecules such as glucose or amino acids are unable to cross a membrane by diffusion, because not only are they polar, but they are too large. Molecules such as this, must diffuse into a cell by facilitated diffusion.
How large non-polar molecules move across a membrane Larger non-polar molecules which are lipid soluble, such as alcohol, can diffuse across the phospholipid bilayer freely as they are able to dissolve in the lipids.
Polar molecules A molecule that while having no overall charge, has an uneven distribution of charges. Typically this can be seen by an uneven distribution of hydrogen atoms around the molecule
Ions A particle that has an overall electrical charge.
Macromolecules, name the four of them Biological macromolecules, the large molecules necessary for life, include carbohydrates, lipids, nucleic acids, and proteins. It is composed of monomers
Monomers a molecule that can be bonded to other identical molecules to form a polymer.
Elements an essential or characteristic part of something abstract.
What monomers are proteins composed of? What are their elements Amino acids (C, H, O, N)
What monomers are carbohydrates composed of? What are their elements Monosaccharides (C, H, O)
What monomers are Nucleic acids composed of? What are their elements Nucleotides (C, H, O, N, P)
What monomers are Lipids composed of? What are their elements Fatty acids and glycerol (C, H, O)
Structure of DNA Each strand is composed of a long chain of monomer nucleotides. The nucleotide of DNA consists of a deoxyribose sugar molecule to which is attached a phosphate group and one of four nitrogenous bases: two purines (a, g) and two pyrimidines (c, t).
Role of DNA in protein synthesis A gene is a segment of DNA that codes for a functional product (mRNA, tRNA, or rRNA). Since the vast majority of genes are transcribed into mRNA and mRNA is subsequently translated into polypeptides or proteins, most genes code for protein synthesis.
Role of mRNA in protein synthesis Messenger RNA (mRNA) is translated into protein by the joint action of transfer RNA (tRNA) and the ribosome
Role of tRNA in protein synthesis The overall role of tRNA in protein synthesis is to decode a specific codon of mRNA, using its anticodon, in order to transfer a specific amino acid to the end of a chain in the ribosome.
Role of rRNA in protein synthesis Ribosomal RNA (rRNA) associates with a set of proteins to form ribosomes. These complex structures, which physically move along an mRNA molecule, catalyze the assembly of amino acids into protein chains.
Transcription Transcription is the process by which the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA).
Translation Translation is the process of translating the sequence of a messenger RNA (mRNA) molecule to a sequence of amino acids during protein synthesis.
Relationship between DNA and proteins Each triplet (gene) codes for a different amino acid that can be built into a polypeptide, hence a protein.
Primary structure of proteins (and bonding) The primary structure refers simply to the order of the amino acids in the polypeptides that make up the protein. Held by peptide bonds
Secondary structure of proteins (and bonding) The secondary structure of a protein refers to the pleating and coiling of the polypeptide as hydrogen bonds form between different regions of the polypeptides. The "pleats" are called beta sheets, and the coils are called alpha helices. Hydrogen bonds
Tertiary structure of proteins (and bonding) The tertiary structure of a protein is the 3-D shape of the protein. It is this aspect of the protein's nature that most determines the specific function of most proteins. Ionic interactions
Quaternary structure of proteins (and bonding) If a protein has quaternary structure, this simply describes that the protein is made of more than a single polypeptide chain. Hydrogen, ionic, covalent
What is the proteome The collection of proteins that an individual has.
Describe globular proteins and provide examples Those that have a tertiary structure, including enzymes and antigens
Describe fibrous proteins and provide examples Have a primary structure and secondary structure, they are long, examples include keratin
Important things made of protein Enzymes, channel proteins, antibodies
What are chromosomes Structures composed of DNA and proteins called histones, nucleic acid and protein are collectively known as chromatin.
Differences between DNA and RNA DNA contains the 5-carbon sugar deoxyribose whereas RNA has he 5-carbon sugar ribose. DNA is double stranded.
What are the bases of DNA A, T, G, C
What are the bases of RNA A, U, G, C
What is a locus The position of a gene on a chromosome
Step 1 of DNA replication A section (called a replication bubble) of DNA is unwound and the strands are separated by DNA helicase enzyme
Step 2 of DNA replication An RNA primer is added to the 3' end of each strand
Step 3 of DNA replication The enzyme DNA polymerase runs down the strand 3' to 5' adding nucleotides according to base pairing. One strand is copied continuously while the other is done in short lengths. They are then joined by ligase resulting in two strands of DNA that are same
Where does DNA replication occur It occurs in the nucleus of the cell.
Step 1 of transcription DNA strands unwound and separated by RNA polymerase
Step 2 of transcription The RNA polymerase then runs along the template strand in a 3' to 5' direction adding RNA nucleotides against DNA strand according to the base pairing rule U to A, A to T, C to G, G to C.
Step 3 of transcription The pre-mRNA separates from the template strand and the DNA strands join back up
Where does transcription take place In the nucleus of a cell
Step 1 to RNA processing The introns are cut out of the pre mRNA, and the exons are ligated together
Step 2 to RNA processing A methyl cap is added to the 5' end of the mRNA
Step 3 to RNA processing A poly-A-Tail is added to the 3' end (poly-A meansa long chain of nucleotides with the nitrogen containing base adenosine
Where does RNA processing occur? In the nucleus
What are introns and exons coding regions (exons) are interrupted by noncoding regions (introns). During transcription the entire gene is copied into a premRNA, whichincludes exonsand introns.Duringtheprocessof RNA splicing, introns are removed and exons joined toformcodingsequence
Step 1 to translation The mRNA enters a ribosome 5' end first
Step 2 to translation tRNA molecules which have an amino acid at one end a trinucleotide of 3 bases called an anticodon at the other, pair with specific complementary on the mRNA (called codons)
Step 3 to translation Peptide bonds form between the amino acids. Forming a polypeptide
Where does translation take place In the ribosomes of cells.
What is an anticodon a sequence of three nucleotides forming a unit of genetic code in a transfer RNA molecule, corresponding to a complementary codon in messenger RNA.
What is the lac operon It is a part of gene regulation, a model for regulation. Its on the desktop
Start and stop codons? a sequence of three nucleotides forming a unit of genetic code in a transfer RNA molecule, corresponding to a complementary codon in messenger RNA. AUG
Promotor regions Promoter regions are sections of a gene that are found before the
start triplet, at the 5' end of the site where transcription will begin. Location of RNA polymerase
Regulator genes? Regulatory genes code for transcription factors. Transcription factors are proteins that control gene
expression at the transcription stage, in other words they control the action of other genes.
Structural genes? Structural genes code for proteins and RNAs that are not involved in gene regulation, they produce
proteins that become part of the structure and the functioning of the organism. For example enzymes
Anabolic reaction? Those that build more complex molecules out of smaller molecules. Energy requiring
Catabolic reactions? Those that break large molecules into smaller ones. Energy releasing
What is the active site of an enzyme The active site of an enzyme is the part of the enzyme that the substrate attaches to.
What is the binding site of an enzyme The binding site of a substrate molecule is the part of the substrate that binds to the active site of an enzyme
How enzymes speed up reactions They lower the activation energy by weakening critical bonds within the substrate. Enzymes change shape to maximise contact with the substrate
Effect of temperature on rate of enzyme action Molecules move faster as temperature rise but if the temperature is too high they denature. The temperature that an enzyme works best at is called the optimum temperature
Effect of pH on enzyme action Enzymes have an optimum pH, anything to far from that will slow down the rate of reaction
Effect of enzyme concentration As the enzyme concentration increases the rate of reaction will increase
Effect of substrate concentration As the concentration of substrate increases, the rate of reaction will increase up to a point where the enzymes are saturated with substrate.
Effect of competitive inhibitors They bind to the active site and prevent a substrate from binding, They can be displaced if the concentration of substrate gets high enough
Effect of non-competitive inhibitors Prevent the substrate from binding to the active site of an enzyme by attaching themselves to another part of the enzyme which changes the shape of the enzyme. They cannot be removed
Effect of cofactors and what are coenzymes A small molecule that binds to the active site which allows some substrates to fit. Coenzymes are organic molecules, one for example includes ATP
What are the energy carrier molecules ATP, NADH, NADPH, FADH, all are similar in function
What is ATP ATP is a coenzyme which can help enzymes join small molecules together to make larger molecules. The energy in ATP molecules is contained in one of its three phosphate bonds, when a phosphate is removed energy is released making it ADP
What is NADH Another carrier molecule of cells, it is used in cellular respiration
What is NADPH Energy carrier molecule for hydrogen in the light dependent stage of photosynthesis
What is FADH It is involved in the electron transport chain
What is the overall equation for cellular respiration C6H12O6 + 6O2 —-36ATP—-> 6CO2 + 6H2O
What are the stages of cellular respiration Glycolysis, the krebs cycle, electron transport chain
Glycolysis…. What occurs and where? Inputs? Outputs? ATP? Oxygen required? Occuring in the cytosol it requires no oxygen. It involves the splitting of one glucose into two pyruvate molecules energy released produces 2 ATP and is used to form 2 NADH
The kreb cycle…. What occurs and where? Inputs? Outputs? ATP? Oxygen required? If oxygen is present two pyruvate move to the matrix of mitochondria and break down, 6 CO2 are formed and the energy released forms 2 ATP and loads 12H+ ions onto NAD and FADH to form 8 NADH and 4FADH2
Electron transport chain…. What occurs and where? Inputs? Outputs? ATP? Oxygen required? Final stage of aerobic respiration, uses oxygen, takes place on cristae of mitochondria, in this 6 water molecules are formed from the electrons donated by NADH and FADH2. 32-34 ATP are produced.
ATP Yields of glycolysis? 2 ATP
ATP yield of krebs cycle? 2 ATP
ATP yield of electron transport chain 32-34 ATP
How efficients Anaerobic respiration in comparison to Aerobic respiration It is much less efficient but occurs quicker
Comparisons of anaerobic respiration in comparison to Aerobic respiration Less atp produced, occurs in cytoplasm, can only be sustained for a short period of time
Overall inputs and outputs of photosynthesis 6CO2 + 12H20 —light and chlorophyll—-> C6H12O6 + 6O2 + 6H20
Light dependent stage Energy from the sun splits water molecules into hydrogen ions which are taken up by hydrogen acceptors, NADP to from NADPH2 and oxygen to create ATP. Only NADPH2 and ATP go to the next stage. Oxygen is a waste product
Light in-dependent stage The hydrogen ions from NADPH2 are combined with the carbon dioxide to form glucose. ATP produced takes part in the anabolic reaction.
Leaves don't absorb green light, only other colours
What colour is best absorbed by leaves Colour at the blue/violet end of the spectrum and at the red end a little less.
Neurotransmitters (paracrine signalling) Produced by neurons, they are held in vesicles within the axon terminal and the vesicles move across to the plasma membrane and release the neurotransmitter into the synapse, They then bind to a specific receptor.
Hormones (Endocrine signalling) Hormones are chemicals that are produced in endocrine glands and travel through the bloodstream
Cytokines Include hormone like chemicals that are involved in the immune response. They are secreted by a range of cells and simulate various leucocytes. These include interferons which stimulate phagocytes
Pheromones Non-protein chemical messengers that are released from one organism, and signal a respond in another individual of the same species
Endocrine chemicals are secreted into the blood and carried by the blood and tissue fluids to the cells they act upon.
Paracrine describes hormone action where hormones are released from cells and bind to receptor on nearby cells and affects their function. Inflammatory responce
Autocrine mode of hormone action to which hormones bind to receptors on to the cell and affects the cell that produces it.
Signal transduction The chain of events that converts an external signal from a signalling molecules, such as hormone or neurotransmitter into a specific cellular response
Step one of signal transduction A signalling molecule binds with a protein receptor on the surface of a target cell
Step two of signal transduction This binding causes a conformational change in the receptor protein
Step three of signal transduction The change in shape of the receptor protein, leads to the activation of a second messenger, inside the cell
Step four of signal transduction The second messenger is produced in large numbers, so that the signal provided by the original ligand is amplified within the cell
Signal transduction in plants (ethylene) Causes ripening of fruit and development of flowers. When one fruit ripens, it releases ethylene, which binds to receptors on the surface of cells of unripe fruit. This signal is transduce in such a way that it stimulates the ripening of that fruit.
Infectious diseases Those that can be passed from one individual to another by contact or in some other way
Non-infectious diseases Diseases that cannot be caught, these include genetic disease.
How are pathogens spread Contact… In droplets in the air(sneezing)…. Sexual intercourse…. Contaminated food and water
Different types of pathogens (non living) Viruses…. Viroids…. Prions…
Viruses Non cellular, non living they are made of nucleic acid and surrounded by a protein coat. The DNA contains genes only used to code to build enzymes necessary to construct new virus particles
Prions a protein that is capable of infecting cells and using the cells organelles and resources to replicate itself. "mad cow disease"
Viroids These are a tiny loop of RNA. They cause disease in plants
Different types of pathogens (living) Bacteria…. Fungi…. Protozoans
Bacteria Prokaryotes which lack a nucleus or any membrane bound organelles.
Fungi Eukaryotic single celled organisms which lack a cell wall. Usually free swimming.
Rational drug design Based on the knowledge of how the structure of a virus enables it to cause disease or complete its life cycle, using that knowledge to block a critical enzyme or receptor to stop the virus.
What is a leucocyte? White blood cells
What are the main leucocytes Phagocytes…. Neutrophils…. Macrophages…. Dendritic cells…. Mast cells
Phagocytes? Leucocytes that engulf foreign matter by phagocytocsis
Neutrophils? The most numerous of the phagocytes. Also the smallest
Macrophages? They are part of the non-specific defences of the body. They play an important role in the specific immune response also as they are antigen presenting cells.
Dendritic cells? They act in the body but are like macrophages. Act as antigen presenting cells in the mucous membranes and intestines
Mast cells? Not phagocytes, they contain granules of a protein called histamine. Mature mast cells are embedded in connective tissues of the body such as skin, and mucous membranes and the connective tissues surrounding blood vessels. They cause blood vesselstodilate
What is lymphocytes a form of small leucocyte (white blood cell) with a single round nucleus, occurring especially in the lymphatic system
What are the lymphocytes? B cells and T cells
B cells? Responsible for what we call the "humoral immune response". This is the specific production of antibodies that are dispatched in the humors of the body to stick onto a specific antigen that has trigger the response
Plasma cells These are the clones of activated B cells that are responsible for making and releasing antibodies
B memory cells These are the clones of activated B cells that are metabolically inactive, but last a long time in a persons body, placing lasting immunity on that person
T cells Are responsible for several aspects of the specific immune response, including the humoral and the cell-mediated responces.
Different types of T cells Cytotoxic T cells…. Helper T cells…. Suppressor T cells…. T memory cells
Cytotoxic T cells These are involved in the cell mediated immune response. They find cells which have foreign antigens, kill them, by releasing enzymes which cause the cell to kill itself
Helper T cells These cells, when selected release interleukin 1 which stimulates B cells and interleukin 2 that stimulates cytotoxic to become very active.
Suppressor T cells Like T helper cells, these cells regulate the activity of Cytotoxic T cells but their action is to slow down cytotoxic T cells, preventing them from attacking too vigorously
T memory cells Like B memory cells, these Cytotoxic T cell clones are metabolically active and last for years
What are large granular lymphocytes( natural killer cells) Very similar in action to Cytotoxic T cells, but they are part of the second line of defence. They are non-specific and circulate the body and kill cells that don't have the normal MHC-1 markers that identifies them as self.
Apoptosis (programmed cell death) Cells will sometime initiate a signal cascade that results in the breakdown of the cytoskeloton
Apoptosis steps 1 Separation from adjacent cells
Apoptosis step 2 Breakdown of cytoskeleton
Apoptosis step 3 Cell shrinkage
Apoptosis step 4 Breakdown of nucleus and membrane bound organelles
Apoptosis step 5 Blebbing of plasma membrane
Apoptosis step 6 budding of plasma-membrane-bound vesicles called apoptotic bodies which
prevent toxic or immunogenic substances from leaking when the apoptotic bodies are phagocytes
What are the two pathways of apoptosis Extrinsic pathway and the intrinsic (mitochondrial) pathway
Apoptosis and cancer When there is a lack of apoptosis caused by mutations in DNA there is an abnormal growth of cells which is cancer
Role of the lymphatic system To collect up excess tissue fluid and deliver it back to the bloodstream. Lymphocytes are found in the lymphnodes.
First line of defence Intact skin, mucous membranes, coughing and sneezing reflexes are all first line defences to prevent disease by stopping pathogens before they enter the body.
The innate immune responce involves phagocytes, inflammation, interferons and the complement system
Inflammation Includes local swelling caused by dilation of arterioles leading to the infected area, this makes blood vessels leaky. This allows phagocytes to move easier out of the blood and into the site of infection
Interferons These are a cytokine secreted by virus-infected cells that make nearby cells more resistant to invasion by viruses
The complement system Is a system of numerous proteins that do various things in the body such as sticking to cells that have antibodies attached to them.
Antigens Markers on the surface of cells. When a pathogen nvades the body it is identified as foreign, by the immune cells(leucocytes). After pathogens are noticed by the B cell for example the B cells multiplies rapidly dividing to produce plasma cells and memory
Antibodies connected with antigens and allow the response to occur.
Antibody structure Composed of two heavy chains and two light chains which give it a Y shape.
Classes of antibodies IgG and IgE
What is the function of IgG antibodies They circulate the body
How does an allergy occur When the plasma cells produce to many IgE cells
What is the function of IgE antibodies They stimulate the mast cells in an allergic response.
Paracrine signalling between leucocytes occurs through cytokines
Plant defences to disease (physical) The cuticle and epidermal cells form an outer barrier for plants much like intact skin in humans.
Plant defences to disease ( chemical) Toxins to insects… Antibiotic chemicals in response to tissue damage by bacteria…. enzymes…. hormones
Blood clotting When a blood vessel is damaged, platelets quickly form a temporary clot to seal the break and minimise blood loss.
Passive immunity Is acquired when the antibodies are received from an outside source rather than being produced by the body. This is only temporary and can come from injections or mothers milk
Active immunity Is acquired when the body is in response to antigen that has entered the body and then produces antibodies.
Induced immunity Occurs because of an injection
Naturally acquired immunity Immunity that is acquired without medical intervention
Primary immune responses Takes place upon the first encounter with a foreign antigen.
Secondary immune responces Antibodies are produced much faster and more are produced.
Herd immunity Unvaccinated individuals are protected because they are surrounded by individuals who are vaccinated making it harder for pathogens to spread.
Name disorders of the immune system Allergy…. Auto immune diseases…. Transplant rejection…. Immunodeficiency diseases…. Rhesus incompatibility
Allergy When the wrong sort of antibody is produced
Auto-immune disorders When the immune system is unable to recognise self and nonself cells the cytotoxic T cells and antibodies destroy self cells.
Transplant rejection Happens when MHC proteins which are antigens identify the tissue as nonself
Immunodeficiency diseases When a persons immune system is not strong enough to keep pathogens at bay
Epidemic outbreak When a disease is widespread within a population for a particular time
Pandemic When a disease is spread beyond country borders
Outbreak Describes the sudden and unexpected appearance of a disease within a population
Antibiotics Compounds that act against the reproduction of Bacteria, they are often effective in preventing the growth of the cell wall. Ineffective at killing virus
Antiviral drugs Drugs that interfere with some aspect of the lytic cycle of a virus, they are ineffective at killing bacteria.
Antiseptics Are chemicals that kill or damage microbes on the body and are usually applied to cuts or burns to prevent infection
Disinfectants Chemicals that kill or damage microbes on inanimate objects such as counters and toilets. Alcohol
Ploidy level Diploid=2n and haploid=n chromosomes. Humans have a 2 sets of 23 chromosomes
Fossil The remains of a prehistoric organism or direct evidence of its existence, which has been preserved usually either petrified or as a mould or cast
Conditions necessary for fossilisation Quickly covered in sediment…. hidden from scavengers…. decreased rate of decomposition….. hard tough exoskeleton…. protection from weather (wind/sunlight water)….. constant humidity….. constant temperature
Why is the fossil record incomplete Because fossilisation is a very uncommon event and many don't live in environments where fossilisation are possible
Why are fossils of some species incomplete Different reasons such as scavenger, rocks also move disassembling them
What is a stratigraphic correlation Means looking at the rock strata that a fossil can be found in and then comparing it to rock strata in another location to find how old it is. This can be done by matching index fossils
Index fossil Easily distinguished fossil, distributed over a wide area, and thought to have existed for a short amount of time, used to calculate other ages of rocks or fossils
Radiometric dating (ABSOLUTE DATING) Absolute dating is determining the age of a rock directly using radiometric techniques using radioactive isotopes such as radiocarbon dating and potassium-argon dating.
Half life of 14C and how old radiocarbon can date back The halflife of radiocarbon 14 is 5730 years. It can date fossils younger than 50,000 years
Halflife of Potassium Argon dating 1.3 billion years
How old is Earth 4.5 billion years
How long has life existed on Earth 3.5 billion years
When did dinosaurs evolve and in what era Mesozoic era 250 million years ago
When did dinosaurs become extinct 65million years ago at the end of the jurassic period.
When did the first hominins (first human like creature) appear 3 MILLION YEARS AGO
When did homosapians first appear 0.2 million years ago
Which countries were part of gondwana Australia.. South America.. Africa.. Antartica.. Papua New Guinea.. Madagascar.. India.. New Zealand
Homologous structure Is a structure found in one species that has the same basic anatomy as a structure found in another species, even though the structures may have different functions. same ancestor different function
Analogous structure Structures found in different species that serve the same function but fundamental differences in their anatomy show that they have not been inherited from a common ancestor. Same function different ancestor
Vestigial structure Structure found in related species that serves no function
Comparative embryology( in terms of VON BAERS LAW) Vons law says that an embryo develops, its development retells a story of evolution.
DNA hybridisation Measuring the similarities amongst DNA using heat
Significance of Mitochondrial DNA They contain their own DNA. It is not shuffled like chromosomal DNA. It is inherited from the mother. Used in the molecular clock
List the sources of variation between members of species Mutation… Crossing over… Independent assortment of non-homologous chromosomes in meiosis…. sexual reproduction…. random mating
Genes Length of DNA coding for a protein
Allele each of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.
How do mutations arise No apparent reason or because of radiation
Point mutations Affect only one base, can be single deletions or additions
Block mutations Chromosomal rearrangement mutations affect multiple genes
Somatic mutations Happen in body cells and cannot be passed to offspring
Germline mutations Happen in the gonads and are inherited by offspring
Structural gene genes that are not regulatory
Regulatory genes Encode a protein that affects the expression of other genes
BMP4 Regulatory gene Determines facial structure in birds. In galapogos finches the heaviness of the beak is determined by the amount of BMP4 and how early it is produced
Selecting agent Tends to kill individuals that are not suited to that environment, this is called selection pressure
Biological fitness in terms of survival and reproduction Measured by the relative contribution to the gene pool of the next generation made by individuals with a particular phenotype
Effect of selection on allele frequencies Natural selection acts on the phenotype, so if the phenotype is favoured then the allele frequency will increase
Complete selection When selecting agents kill individuals who are selected against.
Partial selection When individuals selected against are made less likely to reproduce
Effect Artificial selection has on gene pools As favourable genes are chosen to be reproduced the gene pool gets smaller.
Geneflow A way that the frequency of alleles in the gene pool of a population can change because individuals are immigrating into the population
Genetic drift When the frequencies of alleles in the gene pool are changed due to chance events
Founder effect Occurs when a small group of individuals from a larger population move to a new location and establish a new population
Convergent evolution(Analogous structures When species that are not related are put to the same selection pressures and become more alike.
Divergent specie(homologous structures) When a two populations of a species are faced with different selection pressures and become less alike
What is a species A group of organisms that can mate and produce viable offspring
What is extinction When a species ceases to exist
What is a primate A primate is a mammal that has opposable thumbs and eyes facing forward
What is a hominid The group consisting of all modern and extinct great apes
What is a homonid The group consisting of all modern humans, extinct human species and other immediate ancestors
Ancestors of human species Homo erectus… Homo neanderthalis
Main features of modern humans Larger brain case… smaller teeth
Out of africa theory States homosapeins evolved in Africa and then spread out from there replacing populations
Cultural evolution Knowledge of humans passed on from generation to generation
Explain the action of restriction enzymes Cuts DNA at a specific recognition site. AATA
Explain and the difference between sticky ends and blunt ends created by restriction enzymes. Sticky ends – DNA fragments with exposed nucleotides Blunt ends- DNA fragments with no exposed nucleotides
Genetically modified organisms GMO
Describe the 4 steps in Polymerase chain reaction to amplify DNA (1,2) 1. Denaturation- heated to 95 degrees –separates strands of DNA. 2. Annealing- cooled to 50-60 degrees Celsius to allow primers to bind to complementary DNA sequence on both strands.
Describe the 4 steps in Polymerase chain reaction to amplify DNA (3,4) 3. Elongation/extension- Temperature increased to 72 degrees – the optimal temperature for Taq Polymerase- TP adds the nucleotides to DNA template strands 4. Cycle is repeated
How does DNA move through electrophoresis gel The gel is porus… DNA is negatively charged
What sized fragments move furthest in gel electrophoresis Small
Stem cells Cells that have not fully differentiated
Ethics of gene cloning enetic testing can have errors – individuals may make decisions regarding abortions, implanting embryos based on information that may be incorrect.