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biology > Protein Synthesis > Flashcards

Protein Synthesis Flashcards

1
Q

5difference between eukaryotes dna and prokaryotes

A

Eukaryotes DNA’s -
linear
associated with histones
has exons and introns
longer

Prokaryotes DNA’s -
circular
has exons only
shorter because doesnt have noncoding DNA

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2
Q

similarities between eukaryotes and prokaryotes DNA

A

both have double stranded dna
both have polynucleotides and both are polymers of nucleotides
both have phosphate groups

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3
Q

where are introns found

A

within a gene

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4
Q

what are the 4 types of RNA

A

Messenger RNA (mRNA) – formed during transcription.

Transfer RNA (tRNA) – involved in translation.

Ribosomal RNA (rRNA) – consist of a large and a small subunit, site of translation.

Interfering RNA (RNAi) – inhibits translation

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5
Q

describe mRNA

A

This is a single stranded polynucleotide chain.

· It is a complementary copy of a single gene, from the TEMPLATE strand of DNA.

· mRNA’s length will vary depending upon the number of bases that make up the gene, so it is much shorter than DNA.

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6
Q

what is a gene

A

· A gene is a sequence of nucleotides that codes for a primary structure of a polypeptide chain.

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7
Q

Contrast DNA and mRNA.

A

DNA is double stranded whereas RNA is single stranded

DNA is longER whereas RNA is shortER

Thymine in DNA whereas Replaced with uracil in RNA

Deoxyribose in DNA whereas Ribose in RNA

DNA has hydrogen bonds whereas mRNA doesn’t have hydrogen bonds

DNA has introns whereas mRNA doesn’t have introns

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8
Q

what is the role tRNA

A

The role of the tRNA molecules is to carry a specific amino acid to the RIBOSOME [site of protein synthesis].

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9
Q

what is a genome

A

complete set of genes in a cell

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10
Q

define proteome

A

full range of proteins that a cell is able to produce.

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11
Q

define loci

A

position of a gene within chromosome

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12
Q

what is an allele

A

a different version / form of a gene

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13
Q

what is the difference between introns and exons

A

Introns - non-coding sequences within a gene of DNA.

Exons - coding sequences within a gene of DNA.

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14
Q

describe the process of transcription

A

(DNA Helicase attaches to) unwinds DNA double helix at site to be transcribed.

· Hydrogen bonds between the two strands are broken, DNA strands separate.

· Only 1 strand acts as a template.

· Complementary free RNA nucleotides associate with exposed DNA bases via complementary base pair rules on the template strand only.

· Uracil to Adenine and Cytosine to Guanine

· RNA polymerase joins adjacent RNA nucleotides together (condensation reaction forming PHOSPHODIESTER bonds)

· Introns are now removed by SPLICING to produce mature mRNA

· mRNA passes out of nucleus via nuclear pore to the RIBOSOME (site of protein synthesis).

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15
Q

describe translation

A

mRNA binds to ribosome
Ribosome finds the START codon
Idea of two codons/binding sites
(Allows) tRNA with complementary anticodons to bind/associate with codon
(Catalyses) formation of peptide bond between amino acids (held by tRNA molecules) using energy from ATP
tRNA released as Ribosome moves along (mRNA to the next codon)/translocation described
Ribosome releases polypeptide into RER when the STOP codon is reached

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16
Q

give 2 features of the genetic code

A

Universal – the same 3 bases on mRNA (codon) / DNA (triplets) code for the same amino acids in all organisms.

Non-overlapping –Each base is only part of 1 triplet (DNA) / codon (mRNA), each base is read once in a triplet

17
Q

what does degenerate mean

A

More than one triplet (DNA)/ codon (mRNA) codes for an amino acid

18
Q

what is a mutation

A

A mutation is any change to the DNA base sequence.

19
Q

what are the consequences of a mutation

A

May alter the SECONDARY STRUCTURE (change the position of the weak Hydrogen)

May alter the TERTIARY STRUCTURE (change the position of the bonds between the R groups of amino) and may alter the BINDING site or ACTIVE site of enzymes and make the protein non-functional.

20
Q

what is a silent mutation

A

where the mutation does not change the amino acid coded for, so will have no effect on the polypeptide chain, because the genetic code is degenerate

21
Q

what does an addition or deletion mutation result in

A

This results in an alteration of the base triplets from the mutation onwards. The reading frame has been shifted to the right / left by one base, and so is known as a frame shift.

22
Q

what are mutations responsible for

A

mutations are responsible for the genetic diversity of populations both in the forces of natural selection and in speciation.

23
Q

what do mutagenic agents do

A

increase the rate of spontaneous mutation

24
Q

give examples of mutagenic agents

A
  • high energy ionising radiation (X rays and gamma ray) because they damage DNA bases
  • DNA reactive chemicals such as benzene, bromine and hydrogen peroxide
  • Biological agents such as some viruses and bacteria
25
Q

what is chromosome non-disjunction

A

failure of homologous chromosomes or sister chromatids to separate properly during cell division, so non-disjunction chromosomes don’t have 1 copy of chromosomes

26
Q

how many chromosomes do humans have

A

46 , 23 pairs

27
Q

what are chromosome pairs 1-22 called

A

autosomes (for things that aren’t sex related)

28
Q

what is a trisomy

A

3 copies of 1 gene (usually at pair 21)

29
Q

what is a homologous chromosome mean

A

one of a pair of chromosomes with the same gene sequence, loci, chromosomal length, and centromere location (look similar)

30
Q

what is an inversion mutation

A

when a segment of bases is reversed end to end

31
Q

what is a duplication mutation

A

a doubling of a part of a chromosome, of an entire chromosome or even whole genome

32
Q

what is a translocation mutation

A

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

33
Q

what are non-homologous chromosomes

A

chromosomes that contain alleles of different genes

34
Q

structure of trna

A

It has regions where the strand is folded over, but it is single stranded. It has a cloverleaf structure held by hydrogen bonds.

It also has a region of 3 bases known as an anticodon.
The anticodon is specific to the amino acid carried by the tRNA and is complementary to the codon on the mRNA.

biology (17 decks)

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