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42 Cards in this Set
- Front
- Back
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Gene mutation |
A change in the amount of,or, arrangement of genetic material in a cell |
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What's the difference between regulatory gene and structural gene |
The regulatory gene- codes and produces repressor protein. It controls the expression of the structural gene. Structural gene-codes and produces the enzymes |
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What is lactose broken down to |
Lactic acid and other sugars |
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Describe how genes are switched on when lactose is present? |
Lactose molecules bind to a different site on the repressor protein, changing its shape. This means it's other binding site can't bind to the operator region. This leaves the promotor region unblocked so rna polymerase can now bind to it and initiate the transcription of mRNA for Lactase genes |
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How to stop codons cause termination |
They don't code for an amino acid |
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Difference between prophase I and II |
Prophase I has homologous pairs lining up to form a covalent and chiasmatas are formed causing crossing over to occur |
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Describe hardy weinbergs principle |
p=frequency of dominant allele q=frequency of recessive allele P=frequency of dominant phenotype Q=frequency of recessive phenotype p+q=1 p2+2pq+q2=1 |
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Operon |
A length of Dna made up of structural genes and control sites. The structural genes code for proteins such as enzymes. The control sites are the operator region and a promotor region |
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What is apoptosis controlled by? |
Cell signals e.g cytokines hormones growth factors nitric oxide |
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How does nitric oxide cause apoptosis |
It makes the inner mitochondrial membrane more permeable to h+ ions upsetting the gradient |
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How does nitric oxide cause apoptosis |
It makes the inner mitochondrial membrane more permeable to h+ ions upsetting the gradient |
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What's the result of too much/little apoptosis? |
Too much- cell degeneration/loss Too little- tumour |
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Differences in meiosis in plants and animals |
In animals in telophase 1 two new nuclear envelopes form and the cell divides by cytokinesis. Chromosomes uncoil. In plants cells go straight from anaphase 1 to meosis 2. In telophase 2 in animals four haploid cells are produced and in plants a tetrad of four haploid cells |
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Metaphase 2 |
Chromosomes arranged themselves on the equator and attach to spindle fibres. |
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Apoptosis |
Enzymes break down cytoskeleton. Cytoplasm becomes densely packed. Blebs form. Chromatin condenses and nuclear envelope breaks down and DNA breaks into fragments. Cell breaks into vesicles which are engulfed by phagocytosis. |
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Which substances cause mutations? |
Tobacco, uv light, x Ray's and gamma rays |
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Why do some mutations have no effect? |
In a non coding region of DNA. Silent mutation still codes for the same amino acid |
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What does beta galactosidase do? |
Hydrolysis of lactose to glucose and galactose |
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What does lactose permease do |
Transports lactose into the cell |
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Homeobox genes |
Control the development of the body plan of an organism, including the polarity and positioning of the organs |
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What is linkage? |
Two or more genes that are located on the same chromosome. The linked alleles are normally inherited together because they don't segregate independently at meosis |
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Sickle cell anaemia |
Mutation in b strands of haem. Abnormal haem is insoluble when deoxygenated forms crystals and deforms red blood cells. It can't fit through capillaries causing a painful crisis! It is codominant but in heterozygous the presence of normal haemoglobin prevents sickling |
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Epistasis |
The interaction of different gene loci so that one gene locus masks or suppresses the expression of another gene locus |
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Recessive epistatis |
9:3:4 |
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Dominant epistatis |
12:3:1 or 13:3 |
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Complementary epistatis |
9:7 |
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What does the hardy weinburg principle assume? |
The population is very large Mating in the population is random No selective advantage for any genotype No mutation,migration it genetic drift |
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What prevents a population from freely interbreeding |
Geographical barriers Seasonal barriers such as climate change throughout the year Reproductive mechanisms |
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Mono phyletic |
A group is one that includes an ancestral organism and all its descendent species |
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% divergence= |
number of substitutions / number of base pairs analysed X100 |
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Clade |
Any group of organisms with haplotypes that are more similar to each other than any other group. A taxonomic group of a single ancestral organism and all its descendants |
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Difference between biological species concept and phylogenetic |
-focuses on evolution rather than similarities between species -greater importance in objective and quantitive molecular analysis -uses rna and DNA sequencing -uses computers and data from nucleic acid sequencing to create cladograms that represent the evolutionary tree of life - makes no distinction between extinct and extant species -focuses on common ancestors -can apply to organisms that produce asexually -no importance of members of same species being able to interbreed to produce fertile offspring |
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How does speciation occur due to geographical isolation? |
Different populations cannot breed. There will be different selection pressures and so different alleles will be adaptive in each. There will be random mutations. a genetic drift occurs |
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What would happen if two species with different chromosome numbers were mated? |
Infertile as there would be no pairing in the offspring. Meiosis can't occur and so no gametes produced |
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Where does the repressor protein bind |
Operator region |
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Ways genetic variation is produced? |
Mutations, crossing over in prophase I, independent assortment of chromosomes in metaphase I, independent assortment of chromatids in metaphase II, homologous chromosomes have different alleles, random mating, gametes not identical |
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Why does meiosis need twice as many stages as mitosis? |
To produce cell with half number of original chromosomes. To seperate both homologous pairs and sister chromatids |
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Problems in pedigree animals |
Inbreeding.Homozygous recessive alleles become more common meaning more recessive diseases. The gene for a desired characteristic may be on the same chromosome as a problem gene. Breeders select for looks rather than health. |
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Advantages of cloning a desirable animal as opposed to mating it |
All offspring will possess the foreign DNA. All offspring will be the same sex. Cloning is quicker. No mating risks such as disease transfer |
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Advantages of cloning a desirable animal as opposed to mating it |
All offspring will possess the foreign DNA. All offspring will be the same sex. Cloning is quicker. No mating risks such as disease transfer |
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Disadvantages of cloning a desirable animal as opposed to mating it |
Cloning may have long term health effects. No genetic variation so more susceptible to diseases. Cloning has a poor success rate due to microbial contamination and technology to do it is expensive |
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Nature of scientific knowledge and importance of scientific community |
It's always changing as new things are being discovered. It is important to check hypotheses and results |
