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biology year 12 > protein synthesis > Flashcards

protein synthesis Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Define the term exon.

A

Base/nucleotide/triplet sequence coding for polypeptide/sequence of amino acids/primary structure;

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2
Q

Describe Transcription in Eukaryotes

A
  1. Hydrogen bonds (between DNA bases) break;
  2. (Only) one DNA strand acts as a template;
  3. (Free) RNA nucleotides align by complementary base pairing;
  4. (In RNA) Uracil base pairs with adenine (on DNA) OR (In RNA) Uracil is used in place of thymine;
  5. RNA polymerase joins (adjacent RNA) nucleotides;
  6. (By) phosphodiester bonds (between adjacent nucleotides);
  7. Pre-mRNA is spliced (to form mRNA) OR Introns are removed (to form mRNA);

THINK - Key word is adjacent
Whenever you see transcription think RNA, RNA polymerase , Pre-mRNA -> mRNA

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3
Q

Describe Translation

A
  1. (mRNA attaches) to ribosomes OR (mRNA attaches) to rough endoplasmic reticulum;
  2. (tRNA) anticodons (bind to) complementary (mRNA) codons;
  3. tRNA brings a specific amino acid;
  4. Amino acids join by peptide bonds;
  5. (Amino acids join together) with the use of ATP;
  6. tRNA released (after amino acid joined to polypeptide);
  7. The ribosome moves along the mRNA to form the polypeptide;

THINK - Translation = a transition
So there is a transition from mRNA to tRNA
tRNA = anticodons & mRNA = codons

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4
Q

Give two structural differences between a molecule of messenger RNA (mRNA) and a molecule of transfer RNA (tRNA).

A
  1. mRNA does not have hydrogen bonds / base pairing, tRNA does; OR mRNA is linear / straight chain, tRNA is cloverleaf;
  2. mRNA does not have an amino acid binding site, tRNA does;
  3. mRNA has more nucleotides;
  4. (Different) mRNAs have different lengths, all tRNAs are similar / same length;
  5. mRNA has codons, tRNA has an anticodon;
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5
Q

What is an allele?

A

(Different) form/type/version of a gene / different base sequence of a gene;

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6
Q

Explain how selection occurs in living organisms (5)

A
  1. Variation due to mutation;
  2. Different environmental/abiotic/biotic conditions / selection pressures;
  3. Selection for different/advantageous, features/characteristics/mutation/ /allele;
  4. Differential reproductive success / (selected) organisms survive and reproduce;
  5. Leads to change in allele frequency;
  6. Occurs over a long period of time;
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7
Q

Define degenerate code

A

More than one codon for one amino acid

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8
Q

Explain what the term non-overlapping DNA means.

A

A base from one triplet cannot be used in an adjacent triplet

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9
Q

A mutation in a gene coding for an enzyme
could lead to the production of a non-functional enzyme. Explain how

A
  1. Change in base sequence (of DNA/gene);
  2. Change in amino acid sequence / primary structure (of enzyme);
  3. Change in hydrogen/ionic/ disulphide bonds;
  4. Change in the tertiary structure/active site (of enzyme);
  5. Substrate not complementary/cannot bind (to enzyme / active site) / no enzyme-substrate complexes form;
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10
Q

Not all mutations in the nucleotide sequence of a gene cause a change in the structure of a polypeptide. Give two reasons why.

A
  1. Triplets code for same amino acid
  2. Occurs in introns /non-coding sequence;
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11
Q

Contrast Eukaryotic DNA and Prokaryotic DNA (3)

A
  1. Eukaryotic DNA is linear whereas Prokaryotic
    DNA is circular
  2. Eukaryotic DNA is associated with histones whereas Prokaryotic DNA is not associated with histones
  3. Eukaryotic DNA contains introns whereas
    Prokaryotic DNA does not contain introns
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12
Q

Contrast DNA and mRNA (3)

A
  1. DNA is double stranded whereas RNA is
    single stranded
  2. DNA is longER whereas RNA is shortER
  3. Thymine in DNA whereas thymine is replaced with uracil in RNA
  4. Deoxyribose in DNA whereas ribose in RNA
  5. DNA has hydrogen bonds whereas mRNA doesn’t have hydrogen bonds
  6. DNA has introns whereas mRNA doesn’t have introns
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13
Q

Explain what the term non - overlapping means (1)

A

a base from one triplet cannot be used in an adjacent triplet

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14
Q

Define what is meant by
Universal code

A

the same three bases on mRNA/DNA code for the same amino acids in all organisms

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15
Q

Describe what happens when the third base of a triplet is altered (2)

A
  1. Silent mutation so it will not change the amino acid coded for
  2. so will have no effect on the polypeptide chain
  3. code is degenerate so more than one codon can code for the same amino acid
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16
Q

Describe what happens when the first base of a triplet is altered (3)

A
  1. will change the amino acid coded for
  2. alters the sequence of amino acids on polypeptide chain
  3. may alter the specific tertiary structure
17
Q

Describe the effect of an addition/deletion mutation towards the end of a sequence of bases. (2)

A
  1. reading frame has been shifted to right/left so causes a frame shift
  2. lesser effect but would still alter some amino acids at end of gene
18
Q

Explain the effect of an addition/deletion mutation at the start of a sequence of bases. (2)

A
  1. reading frame has been shifted to right/left so causes a frame shift
  2. all triplets coding for polypeptide would be altered so all amino acids would be altered
19
Q

Name 3 types of mutagenic agents and give 2 examples for each

A
  1. High energy ionising radiation - X rays and gamma rays
  2. DNA reactive chemicals - benzene and bromine
  3. Biological agents - viruses and bacteria
20
Q

Name 3 chromosomal mutations

A
  1. Inversion Mutations
  2. Duplication Mutations
  3. Translocation Mutations
21
Q

What happens during an inversion mutation? (1)

A

a segment of bases is reversed end to end

22
Q

What happens during a duplication mutation? (1)

A

a doubling part of a chromosome, of an entire chromosome, or even the whole genome - a section of DNA is duplicated

23
Q

What happens during a translocation mutation? (1)

A

groups of base pairs relocate from one area of the genome to another, usually between non-homologous chromosomes

24
Q

Describe the difference between stabilising selection and directional selection (1)

A

Stabilising selection favours the average whereas directional selection favours an
extreme phenotype

25
Q

Give two types of molecule from which a ribosome is made

A

rRNA and ribosomal proteins

biology year 12 (20 decks)

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