Genetics

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  • Created by: Sopha8
  • Created on: 26-05-14 21:04
Describe the structure of DNA? what propertise does it give
double helix (stable), 2 strands of polynucleotides-made of nucleotides-phosphate with deoxyribose sugar attached to base, sugar-phosphate backbone (phosphate on sugar of another nulceotide) paired structure-replication, long, coiled-fit in nuclues
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What are the bases in DNA? how are they arranged?
Guanin, cytosine, adenine, thymine. specific base pairing (A with T, C with G)
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How is DNA stored in eukaryotes and prokaryotes?
eu- chromosomes, wound round histones, pro-shoter, circular, condenses by supercoiling
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What is the function of genes?
section of DNA, order of nulceotide bases determines order of amino acids = code for proteins, 3 bases from 1 amino acid (triplet) prtoteins and enzymes formed, enzyme control metabolic pathways-development
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Explain why a code in DNA is degenerate
more than 1 triplet can code for same amino acid
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What is non-coding DNA and multiple repeats?
in eu- dont code for amino acids, called introns, multiple repeats are regions outside gene that repeats DNA sequence over and over, also dont code for amino acids
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What is a homolgous chromosome?
each human body cell has 23 pairs of chromosomes (46 in total), homolgous=pairs of matching chromosomes, same size and genes but may have different alleles
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What is gene mutations?
changes in base sequence of DNA, produce new alleles, can make enzymes acitve site wrong shape so non-functional
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What is a diploid and halpoid cell?
dip=normal body cells, 2 of each chromosome (1mum 1dad) haploid= half number of chromsomes (one copy of each)-gamete
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What are the stages of meiosis?
1. DNA unravels and replicates to form sister chromatids 2.sister chromatids arrange into homologous pairs 3.line up on equator 4.1st divsion-homolgous pairs seperated 5.2nd sister chromatids seperated- 4 haploid cells prouduced (gametes)
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How os genetic variation achieved in meiosis?
1. crossing over of chromatids, during meiosis 1, different combinations of alleles 2.indepedant segregation-different combinations of paternal and maternal chromosomes go into each cell
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What is gentic diversity?
variety in DNA- within species vaires little as members have same genes, but have alleles creating diversity
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What are the factos affecting gentic diversity?
increase=mutaions in DNA to form new alleles & gene flow-different alleles move between pop as inderviduals migrate, decrease=founder effect, gentic bottleneck and selective breeding
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Exaplain gentic bottleneck
event causes reduce in population -less different alleles in gene pool, surviors reproduce so larger pop with less different alleles
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What is the founder effect?
few organisms from pop break off to form new colony, small number of alleles contributed to gene pool, inbreeding means higher risk of gentic diseases
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What are the positives and negatives for selective breeding?
+= higher yields, increased resistance so less pestisides used & tolerance of conditions, - = health problems? only that type of organism being bred, similar alleles so reduces different alleles in gene pool, susceptible to new dieases
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Card 2

Front

What are the bases in DNA? how are they arranged?

Back

Guanin, cytosine, adenine, thymine. specific base pairing (A with T, C with G)

Card 3

Front

How is DNA stored in eukaryotes and prokaryotes?

Back

Preview of the front of card 3

Card 4

Front

What is the function of genes?

Back

Preview of the front of card 4

Card 5

Front

Explain why a code in DNA is degenerate

Back

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