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biology > Protein Synthesis And DNA > Flashcards

Protein Synthesis And DNA Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is a gene?

A

A small section of DNA

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2
Q

How do genes control an organisms phenotype

A

Genes code for specific Amino acids to produce a specific protein/polypeptide

E.g enzymes that control biochemical reactions

Therfore control an organisms development and activities

Along with environmental factors genes determine phenotype

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3
Q

What determines an organisms phenotype?

A

Along with environmental factors genes determine phenotype

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4
Q

What is a locus

A

The position on the chromosome where a gene is found

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5
Q

What is a sequence of 3 bases on DNA called

A

Triplet

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6
Q

Describe the difference between intros and exons

A

Exons= expressed

Introns=not expressed

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7
Q

How many bases code for an Amino acid?

A

3

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8
Q

How did scientists conclude how many bases coded for an Amino acid?

A

If 1 base coded for 1 Amino acid there would be 4 Amino acids

If 2 bases coded for 1 Amino acid there would be 8 Amino acids

If 3 bases coded for 1 Amino acid there would be 64 Amino acids which are plenty to code for all 20 naturally occuring Amino acids

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9
Q

How many Amino acids are there

A

20

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10
Q

Do chloroplasts have more or less genes than mitochondria, why?

A

More because Photosynthesis requires more enzymes than Respiration

Enzymes are proteins that are coded for by genes

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11
Q

Name the main features of the genetic code

A

Degenerate

Non overlapping

Universal

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12
Q

What does degenerate code mean

A

One Amino acid can be coded for by various triplet codes

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13
Q

What does non overlapping mean

A

Every base is only read once

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14
Q

What is meant by a universal code?

A

Same triplets usually code for the same Amino acids in all organisms

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15
Q

How does the genetic code provide indirect evidence for evolution?

A

Universal code means there is a shared biochemistry so indirect evidence for shared ancestor

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16
Q

What does non functional DNA always start and end in?

A

Start with triplet coding for methanionine

End with stop codon

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17
Q

Compare where the genetic code if found in prokaryotes and eukaryotes

A

Pro= cytoplasm

Eu= nucleus

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18
Q

Compare the name of the molecule where the genetic code is found in prokaryotes and eukaryotes

A

Pro= nucleiod or plamsid

Eu= chromosome

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19
Q

Compare the shape of the genetic code found in prokaryotes and eukaryotes

A

Pro= circular

Eu= linear

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20
Q

Compare the association of proteins in the genetic code found in prokaryotes and eukaryotes

A

Pro=none

Eu= with histones

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21
Q

Compare the length of the genetic code found in prokaryotes and eukaryotes

A

Pro= short

Eu= longer

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22
Q

Compare the prevalence of Introns in the genetic code found in prokaryotes and eukaryotes

A

Pro= none

Eu= yes

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23
Q

Do prokaryotes have Introns?

A

No, only exons

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24
Q

Do the genes of chloroplast and mitochondria have Introns?

A

No, same a prokaryote

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25
Q

When are chromosomes visible

A

During semi-conservative DNA replication

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26
Q

What is the difference between sister chromosomes and homologous chromosomes?

A

Sister chromatids are genetically identical and joined by centro mere

Homologous pairs are not genetically identical and aren’t joined by a centromere

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27
Q

What phase of the cell cycle are chromosomes visible

A

Synthesis

28
Q

What are sister chromatids?

A

Genetically identical arms of a chromosome

29
Q

Describe how DNA is arranged

A

Double helix,
wound around histones (DNA histone complex)
Which are coiled and looped
Compact into a chromosome

30
Q

Why are the numbers of chromosomes in organisms usually even

A

So that they can pair up for DNA replication

31
Q

Define homologous chromosomes

A

Pair of chromosomes with the same genes at same locus but not genetically identical

One maternal one paternal

32
Q

What is the diploid number

A

23 homologous pairs

33
Q

What does n stand for in 2n

A

Haploid number

34
Q

How is the diploid number represented algebraically

A

2n

35
Q

What is the haploid number

A

23 chromosomes (not paired)

36
Q

Why are gametes haploid

A

So that upon fertilización the diploid number is restored

37
Q

What is an allele

A

A form of gene

38
Q

How do mutations cause a different polypeptide to be synthesised?

A

Mutations cause a different base sequence creating different allele meaning different protein is coded for.

39
Q

Define genome

A

Complete set of genes in a cell (including mitochondria)

40
Q

Define proteome

A

Complete set of proteins able to be produced by a genome

41
Q

Give difference between definition of proteome in proteome and complete proteome

A

Complete Proteome= proteins produced by specific cell under specific conditions

Proteome = complete set of proteins produced by a genome

42
Q

Describe the structure of mRNA

A

Single stranded helix
Short
Polynucleotide polymer

43
Q

What are codons

A

Three bases on a strand of MRNA

44
Q

Why does MRNA need to be produced

A

Because DNA is too large to exit the nucleus

MRNA is able to diffuse out of the nucleus via a nucleur pore

45
Q

Describe and explain the chemical stability of MRNA

A

Not very stable, no hydrogen bonds

Easily broken down

Prevents any unwanted protein Synthesis to reduce waste

46
Q

Describe the structure of tRNA

A

Clover-leaf shape

Anticodon loop

One end of Polynucleotide chain extends beyond the other allowing for Amino acid attachment

Folds back on itself so has H bonds

47
Q

How many TRNA molecules are there and why

A

64 to account for all 64 combinations of bases

48
Q

What are the different types of RNA

A

TRNA-bring Amino acids to ribosome
MRNA- transfer genes for protein Synthesis
RRNA - make up ribosome

49
Q

Order DNA MRNA and TRNA in increasing size

A

TRNA MRNA DNA

50
Q

Define functional RNA

A

RNA not involved in protein Synthesis

51
Q

What sugar is TRNA made of

A

Ribose

52
Q

What is the func of MRNA

A

Act as scaffold and template for protein Synthesis

53
Q

What is the func of TRNA

A

Carry Amino acids to ribosome

54
Q

What determines the amount of TRNA and RRNA present in a cell

A

Metabolic activity

55
Q

What enzymes are involved in transcription

A

DNA helicase

RNA polymerase

56
Q

Describe how transcription occurs

A

DNA helicase breaks the hydrogen bonds between bases causing DNA to unwind and reveal template strand

Hydrogen bonds form between complementary bases on DNA and free RNA nucleotides (complementary base pairing).

RNA polymerase attaches to start of template and catalyses condensation reaction between RNA nucleotides to form phosphodiester bonds.

Pre-mRNA forms

RNA polymerase reaches stop codon and detaches

Splicing

57
Q

Why are only 12 bases exposed at a time during transcription

A

DNA rejoins once RNA polymerase passes

58
Q

Name the stages of protein Synthesis

A

Transcription

Translation

59
Q

Describe how Splicing occurs

A

Introns are removed from PRE-MRNA forming mRNA

60
Q

Why is only one Polynucleotide strand a template in transcription

A

RNA polymerase has specifically shaped active site so only moves in one direction down strand

61
Q

Why is Splicing important

A

Without it a non-functional protein or no protein would be produced

62
Q

State what is meant be translation

A

Synthesis of polypeptide chain

63
Q

Describe translation

A

MRNA associates with ribosome so 2 codons are in ribosome

TRNA’s with complementary Anticodons form H bonds with codon on mRNA

Peptide bond forms between Amino acids on tRNA using enzymes and ATP in condensation reaction

Ribosome moves forward on codon repeating process as tRNA molecules are released

At stop codon release factor causes ribosome, tRNA and mRNA to detach.

Released polypeptide Folds and accosiates with prosthetic groups

64
Q

What is a polysome

A

Multiple ribosomes working on a mRNA strand at once

65
Q

Why do polysomes form?

A

Faster production of polypeptide

66
Q

How can you tell where the start of an mRNA molecule is?

A

The longest polypeptide chain coming off a ribosome= near end

biology (28 decks)

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