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Genetics Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is biodiversity

A

variety of organisms in an ecosystem

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2
Q

What is species diversity

A

number of different species within an area

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3
Q

Benefits of high species diversity

A
  • stable ecosystem
  • each species is less likely to become extinct
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4
Q

How to measure species diversity for an area

A
  • species diversity index
  • considers the number of different species and how many individuals there are for each species
  • larger species diversity index = larger species diversity
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5
Q

How does deforestation lower species diversity

A
  • decreases plant species diversity
  • less variety of habitats
  • less variety of food sources
  • decreases animal species diversity
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6
Q

How does agriculture/farming reduce species diversity

A
  • deforestation to make space for farm
  • selectively breed plants and animals
  • use pesticides to kill other species
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7
Q

What is classification

A

placing organisms into groups

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8
Q

What is hierarchical classification

A

large groups divided into smaller groups without overlap

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9
Q

What is a species

A

a group of individuals with similar characteristics that can interbreed to produce fertile offspring

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10
Q

Why are the offspring from 2 different species infertile

A

offspring will have an odd number of chromosomes so can’t perform meiosis, so cant’t produce gametes

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11
Q

What is phylogenetic classification

A

species arranged into groups based on their evolutionary origins and relationships

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12
Q

What are 3 ways of comparing relationships between different species

A
  • DNA hybridisation; comparing DNA base sequence
  • A A sequence; comparing A A sequence for the same protein
  • Protein shape; comparing shape of same protein using immunological technique
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13
Q

What is variation

A

difference in characteristics between organisms

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14
Q

Two types of variation

A
  • intraspecific; differences between organisms of the same species
  • interspecific; differences between organisms of different species
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15
Q

Causes of intraspecific variation

A
  • genetic factors; same genes but different alleles
  • environmental factors
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16
Q

Causes of interspecific variation

A
  • genetic; different genes and different alleles
  • environmental factors
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17
Q

Name two types of characteristics

A
  • discontinuous
  • continuous
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18
Q

Properties of discontinuous characteristics

A

characteristics fall into certain groups with no overlap based on genetics only

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19
Q

Properties of continuous characteristics

A

characteristics show a range determined by genetics and environment

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20
Q

What is genetic diversity

A

number of different alleles of genes in a population

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21
Q

Benefit of high genetic diversity

A

species able to adapt with changes in the environment

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22
Q

What can reduce genetic diversity

A

small population size

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23
Q

Describe the principles of natural selection

A
  • random mutation can produce new alleles of a gene
  • the new alleles may benefit the possessor, leading to an increased chance of survival and increased reproductive success
  • the advantageous allele is passed onto the next generation
  • over several generations, the new allele will increase in frequency in the population
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24
Q

Name 2 types of selection

A
  • stabilising
  • directional
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25
Q

What is stabilising selection

A

when the environment favours those with the most common characteristic, so those on the extreme die out; common characteristic increases in proportion

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26
Q

What is directional selection

A

when the environment favours those with the uncommon, extreme characteristics; overtime, becomes the common characteristic

27
Q

What is a gene

A

a section of DNA that codes for a protein

28
Q

Components of a gene

A
  • intron
  • exon
29
Q

Difference between intron and exon

A

exon codes for protein, intron doesn’t

  • intron = non-coding DNA
  • exon = coding DNA
30
Q

How does a gene code for protein

A
  • gene is made of a sequence of bases
  • each 3 bases code for 1 amino acid (triplet code)
  • so the sequence of bases determines sequence of triplet codes which determine sequence of amino acids
31
Q

Properties of triplet code

A
  • degenerate; each amino acid has more than one triplet code
  • non-overlapping; each base is only read once
32
Q

How does a mutation lead to a non-functional enzyme

A
  • change in base sequence
  • change in sequence of triplet codes
  • change in sequence of amino acids
  • change in primary structure
  • change in hydrogen, ionic and disulfide bonds
  • change in tertiary structure
  • change in active site shape
  • substrate no longer complementary so no more ES complexes can be formed
33
Q

How is a protein assembled

A

by transcription and translation

34
Q

What is transcription

A

production of a single stranded complementary copy of a gene (mRNA)

35
Q

What is translation

A

use sequence of codons on mRNA to assemble protein (tRNA brings in amino acids)

36
Q

Define codon

A

a sequence of three bases on mRNA that codes for a specific amino acid

37
Q

Define anticodon

A

a sequence of three bases at one end of a tRNA molecule that’s specific to an mRNA codon

38
Q

Name differences between DNA and RNA

A
  • DNA, deoxyribose. RNA, ribose
  • DNA, thymine. RNA, uracil
  • DNA, double stranded. RNA, single stranded
39
Q

What is mRNA (messenger RNA)

A

single stranded complementary copy of a gene which carries the code for assembling protein

40
Q

What is tRNA (transfer RNA)

A
  • single stranded RNA folded over into a clover shape held by hydrogen bonds between bases
  • has amino acid on top
  • has anticodon at bottom
  • anticodon binds to complementary codons on mRNA
41
Q

Describe the process of transcription

A
  • DNA helicase breaks the hydrogen bonds between complementary bases
  • two separate strands are formed, 1 coding, 1 template
  • free RNA nucleotides align by complementary base pairing
  • uracil is in place of thymine
  • RNA polymerase joins adjacent nucleotides by phosphodiester bonds
  • this leaves pre-mRNA
  • its introns are removed by splicing to form mRNA
42
Q

Differences between tRNA and mRNA

A
  • tRNA is clover leaf shape, mRNA is linear
  • tRNA has hydrogen bonds, mRNA doesn’t
  • tRNA has amino acid binding site, mRNA does not
  • tRNA has anticodon, mRNA has codon
43
Q

Describe the process of translation

A
  • mRNA attaches to ribosomes on RER
  • tRNA anticodons bind to complementary mRNA codons
  • tRNA brings a specific amino acid
  • amino acids join by peptide bonds with the use of ATP
  • tRNA is released after amino acid joined to polypeptide
  • ribosome moves along mRNA to form polypeptide
44
Q

What does meiosis produce

A

4 genetically different cells (haploid)

45
Q

Benefits of meiosis

A

produces gametes which will be used in sexual reproduction in animals and plants

46
Q

Name the stages of meiosis

A
  • interphase
  • meiosis I
  • meiosis II
  • cytokinesis
47
Q

What happens in interphase

A
  • protein synthesis
  • DNA replication
  • organelle synthesis
48
Q

What happens in meiosis I

A
  • prophase I; DNA coils to form chromosomes, nucleus breaks down, spindle fibres form
  • metaphase I; homologous pair of chromosomes line up at centre of cell and attach to spindle fibre via the centromere
  • anaphase I; spindle fibres pull, homologous pair of chromosomes separate to opposite poles via independent assortment
  • telophase I; chromosomes uncoil, nucleus reforms (left with 2 nuclei)
49
Q

What happens in meiosis II

A
  • prophase II; DNA coils to form chromosomes, nucleus breaks down, spindle fibres form
  • metaphase II; chromosomes line up at centre of cell and attach to spindle fibres via centromere
  • anaphase II; spindle fibres pull, centromere splits, sister chromatids move to opposite end of pole by independent assortment
  • telophase II; chromatids uncoil, nucleus reforms (left with 4 genetically different nuclei)
50
Q

What happens in cytokinesis

A

cell separates into 4, each receives nucleus and cytoplasm

51
Q

How does meiosis produce variation

A
  • crossing over
  • independent assortment
52
Q

What is crossing over

A

homologous pair of chromosomes move towards each other and exchange genetic material

53
Q

What is independent assortment

A

produces a mix of alleles from paternal and maternal chromosomes in a gamete

54
Q

Define proteome of a cell

A

the full range of proteins a cell can produce

55
Q

Define genome of a cell

A

the complete set of genes in a cell

56
Q

What happens to DNA mass in meiosis

A

quarters

57
Q

What happens to chromosome number in meiosis

A

halves

58
Q

What is mutation

A

changes in sequence of nucleotides in a DNA molecule

59
Q

Name 2 types of mutation

A
  • chromosome mutation
  • gene mutation
60
Q

What causes mutation

A

random or due to mutagens

61
Q

What is a chromosome mutation

A
  • homologous pair of chromosomes don’t separate in meiosis, so either inherit one extra or one less chromosome (non-disjunction)
  • in plants, inherit more than one diploid set of chromosomes (polyploidy)
62
Q

What is a gene mutation

A

a change in the base sequence of DNA

63
Q

Name 3 types of gene mutation

A
  • substitution; replace one base for another, changes one triplet code
  • deletion; removing a base
  • insertion; adding a base
64
Q

What do insertion and deletion cause

A

frameshift mutations

Biology (5 decks)

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