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Biology > Protein Synthesis > Flashcards

Protein Synthesis Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is a locus

A

A gene located in a particular position on dna

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2
Q

How many amino acids regularly occur in proteins

A

20

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3
Q

What does degenerate refer to

A

Most amino acids are coded for by more than 1 triplet

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4
Q

What does non overlapping mean

A

Each base is part of only one triplet

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5
Q

What does it mean when the genetic code is universal

A

Each triplet codes for the same amino acid in all organisms

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6
Q

What are exons

A

Base sequences coding for sequence of amino acids

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7
Q

What are introns

A

Non coding sequences

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8
Q

What is the difference between prokaryotic and eukaryotic DNA

A

In prokaryotic cells, there is no nucleis and the dna molecules are short, circular, contain plasmids and are not associated with proteins. In eukayotic cells there is a nucleus with nuclear envelope and the dna molecule is very long, linear, associated with histones (proteins) and contains no plasmids

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9
Q

How is a chromosome formed

A

Dna molecules, in association with histones, form chromosomes

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10
Q

What is significant about the mitchondria and chloroplasts of eukaryotic cells

A

Contain dna similar to prokaryotes: short, circular and not associated with proteins

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11
Q

What is a gene

A

A base sequence of dna that codes for the amino acid sequence of a polypeptide and functional RNA (including ribsomal rna and trna)

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12
Q

Where is a gene located

A

A gene occupies a fixed position called a locus on a particular dna molecule

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13
Q

What are 3 features of the genetic code

A

Universal, non overlapping and degenerate

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14
Q

Much of the nuclear dna in eukaryotes doesn’t what

A

Code for polypeptides

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15
Q

What is a homologuous pair

A

Two chromosomes that cary the same genes but not the same alleles of the genes

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16
Q

What is an allele

A

One of a number of alternate forms of a gene

17
Q

What is the genome

A

The complete set of genes in a cell (including those in mitochondria and chloroplasts)

18
Q

What is the proteome

A

The full range of proteins produced by a cell/ genome

19
Q

What is rna

A

A single stranded polymer, made up of repeating mononucleotide subunits

20
Q

Describe the structure of an rna nucleotide

A

Contains the pentose sugar RIBOSE, a phosphate group and one of the organic bases A,C,G or URACIL

21
Q

Describe the structure of mrna

A

Long, single, linear strand with no hydrogen bonds. Its length and quantitity varies as its base sequence is determined by dna. It also has codons (3 bases complementrary to dna) amd its structure is less stable than trna and dna

22
Q

Describe the structure of trna

A

Small, single strand folded into clover leaf shape. It contains hydrogen bonds and has an anticodon which is specific to one amino acid. Its length stays the same

23
Q

Describe the process of transcription

A
  1. Dna helicase unwinds and unzips the dna molecule, breaking H bonds and exposing bases on a template strand 2. Free activated rna nucleotides pair with complementary bases 3. Rna polymerase joins nucleotides into strand until stop code is reached 4. Pre mrna detaches and is spliced into mrna by removing introns 5. Mrna leaves nucleus via pore into cytoplasm where it attaches to ribosome
24
Q

What is the difference between prokaryotic and eukaryotic transcription

A

In prokaryotic cells, transcription directly results in the production of mrna from dna but in eukaryotic cells, transcription produces pre mrna which is spliced (removing introns) to form mrna

25
Q

Describe the process of translation 1-3

A
  1. A ribosome attaches to the start codon on mrna 2. The trna molecule with the complementary anticodon sequence moves to ribosome and pairs with codon on mrna, the trna carries a specific AA 3. A trna molecule with complementary anticodon pairs with next codon on mrna, trna carries another AA
26
Q

Describe the process of translation 4-7

A
  1. The ribosome moves along the mrna, brining together 2 trna molecules at a time 5. The 2 amino acids on trnas are joined by a peptide bond using an enzyme and energy from atp 6. Ribosome moves to 3rd codon, linking AAs on 2nd & 3rd trnas and the 1st is released & free to collect another AA = polypeptide is formed 7. Process continues until ribosome reaches stop code
27
Q

What is a gene mutation

A

A change in the quantity or base sequnce of dna/ chromosomes

28
Q

Gene mutations can arrise spontanously during dna replication, true or false?

A

True

29
Q

What types of gene mutations are there

A

Base substitution and base deletion

30
Q

What happens in substitution of bases

A

A nucleotide in a dna molecule is replaced with another nucleotide that has a different base

31
Q

What can be the effects of a substitution of bases

A

The primary structure will differ so a different polypeptide may be produced, means bonds that form tertiary structure may change so the shape of active site may change so its no longer complementary to substrate to form ecs

32
Q

Why do not all base substitutions have an effect

A

Not all cause a change in the sequence of AAs as the genetic code is degenerate (most AA coded for by more than one base triplet/codon)

33
Q

What problem does base deletion cause

A

Sequences of dna are read in units of 3 so a deleted nucleotide cause all triplets to be read differently as each has been shifted to the left by one. This can create different polypeptides (won’t function correctly)

34
Q

What is a chromosome mutation

A

Changes in the structure or number of whole chromosomes

35
Q

What are the two forms of chromosome mutation

A

1.changes in whole sets of chromosomes, where organisms have 3 or more sets (polyploidy) 2.changes in number of chromosomes, where pairs fail to separate in meiosis (non disjunction) so gamete has 1 more/ less chromosome

36
Q

What are mutagenic agents (give examples)

A

Exposure to mutagenic agents can increase the rate of mutations, examples are high energy ionising radiation (alpha, beta, gamma radiation) and chemicals like nitrogen dioxide or benzopyrene (in tabacco)

37
Q

What is one advantage of showing the genetic code as base sequences on mRNA rather than dna

A

As ribosomes assemble polypeptides using the mRNA code. Dna has 2 strands, each with a different complementary base sequence

Biology (32 decks)

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