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Biology > Protein synthesis and selection > Flashcards

Protein synthesis and selection Flashcards

1
Q

What bonds are nucleotides joined by

A

phosphodiester bonds

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2
Q

Structures in DNA nucleotide

A

phosphate group
deoxyribose sugar
base

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3
Q

purine bases

A

adenine
guanine

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4
Q

pyrimidine bases

A

thymine
cytosine

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5
Q

what is adenine matched with

A

thymine

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6
Q

what is cytosine matched with

A

guanine

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7
Q

difference between eukaryotic DNA and prokaryotic DNA

A

linear vs circular
histones vs no histons
introns vs no introns

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8
Q

RNA nucleotide contents

A

phosphate groups
ribose sugar
base

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9
Q

how is mRNA different to DNA

A

double stranded vs single stranded
longer vs shorter
GC + AT vs GC + AU
hydrogen bonds vs no hydrogen bonds
introns vs no introns

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10
Q

mRNA characteristics

A

single stranded
shorter than DNA
GC + AU

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11
Q

tRNA characteristics

A

1 polynucleotide chain
75 nucleotides
single stranded
hydrogen bonds
amino acid attachment site
anticodon

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12
Q

name the 2 protein synthesis processes

A

transcription
translation

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13
Q

Transcription steps

A

-DNA helicase breaks H bonds between two strands and unwinds DNA double helix
-DNA strands separate
-only 1 strand used as a template
-free nucleotides bind to exposed DNA bases via complementary base pair rules on template strand
-U to A + C to G
-RNA polymerase joins RNA nucleotides together by forming phosphodiester bonds
-introns are removed via splicing to produce mature mRNA
mRNA passes out of nucleus via nuclear pore to ribosome

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14
Q

translation steps

A

-mRNA binds to ribosome
-mRNA has two binding sites
-allows tRNA with anticodons to bind
-catalyses formation of peptide bond between two amino acids
-moves along to next codon

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15
Q

3 ways to describe genetic code

A

-universal
-non overlapping
-degenerate

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16
Q

what does universal genetic code mean

A

the same 3 bases on DNA code for the same amino acid in all organisms

17
Q

what does non-overlapping genetic code mean

A

each base is only 1 triplet code

18
Q

what does degenerate genetic code mean

A

more than 1 triplet DNA codes for an amino acid

19
Q

mutation definition

A

change to a single base in DNA base sequence of a gene
mutations occur randomly and could happen spontaneously

20
Q

result of mutation

A

-may result in a change in the PRIMARY STRUCTURE OF POLYPEPTIDES sequence of amino acids in the polypeptide chain
-may alter the SECONDARY STRUCTURE by changing the position of the weak hydrogen bonds affecting the alpha helices and beta-pleated sheets
-may alter the TERTIARY STRUCTURE by changing the position of the weak Hydrogen, Ionic bonds between the R groups of amino acids and the Disulphide bonds
-and may alter the ACTIVE site of enzymes and make the protein non-functional.

21
Q

silent mutation

A

-mutation does not change the amino acid coded
-so will have no effect on the polypeptide chain
-as DNA code is degenerate

22
Q

substitution mutation

A

a substitution of a base with another base

23
Q

what happens if there is a mutation for the STOP codon

A

-cause the growing polypeptide chain to terminate prematurely
-may not be able to perform its intended function

24
Q

addition/deletion mutations

A

-nucleotide added or deleted
-alteration of base triplet from the mutation onward
-reading frame has been shifted and is known as a frameshift
-addition/deletion that occurs towards the end of a sequence of bases would have a lesser effect but still alter some amino acids at the end of a gene

25
Q

mutagenic agents

A
  1. high energy ionising radiation x-ray and gamma ray
  2. DNA reactive chemicals such as benzene or bromine
  3. biological agents such as virus and bacteria
26
Q

chromosomal mutations

A

-chromosome nondisjunction
-too many chromosomes produced

27
Q

inversion mutation

A

-when a segment of bases is reversed end to end

28
Q

duplication mutation

A

-doubling of a part of a chromosome OR of an entire chromosome OR even the whole genome

29
Q

translocation mutations

A

when a group of base pairs relocate from one area of the genome to another
usually between non-homologous chromosomes

30
Q

allele definition

A

different versions of the same gene

31
Q

genetic diversity definition

A

number of different alleles of genes in a population

32
Q

natural selection definition

A

-organisms that are better adapted to their environment survive and reproduce
-in greater numbers
-resulting in the increase of the frequency of the advantageous allele within the population

33
Q

stabilising selection and example

A

-occurs in all populations where environment is stable.
-selection pressure at both ends of distribution.
-favours the average.
-tends to eliminate extremes.
-reduces variability and the size of the range within population.
-reduces opportunity for evolutionary change
-birth mass

34
Q

directional selection and example

A

-mean in population represents optimum phenotype for existing conditions
-environmental change produces new selection pressure that favours an extreme phenotype
-changed conditions, favour allele combination necessary for survival
-some organisms will possess the new optimum phenotype (allele combination)
-over time, selection means this allele combination will predominate
-the mean phenotype will shift
-eg. thicker fur for mice

35
Q

disruptive selection

A

-is the opposite of stabilising selection
-environmental has selection pressures that favour 2 extreme phenotypes
-when conditions change the optimum phenotypes necessary for survival will also change
-some organisms will possess the new extreme optimum phenotypes
-over time selection means these 2 extremes will dominate and the mean will shift in both directions of extremes
-it is the least common type of selection but it is the most important in evolution

36
Q

what are viable counts of bacteria

A

counts living cells only

Biology (29 decks)

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