Topic 4A: DNA, RNA and Protein Synthesis Flashcards

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1
Q

How does Eurkaryotic cells store DNA?

A

As linear DNA molecules that are threadlike structures each made up of one long molecule of DNA and associated with histone proteins

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2
Q

What do histone proteins do

A

Helps support the DNA the DNA is then coiled up very tightly to make a compact compound

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3
Q

In eukaryotes what has its own DNA

A

mitochondria and chloroplasts, similar to prokaryotes DNA (circular and shorted)

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4
Q

What is DNA like it prokaryotes

A

Shorter and circular, not wound around proteins condenses a to fit into the cells by super coiling

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5
Q

What does DNA contain

A

Genes

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6
Q

What is a gene

A

Sequence of DNA bases that codes for either a polypeptide or functional RNA

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7
Q

What determines order of amino acids of a polypeptide

A

Order of bases in a gene, different polypeptides have different number and order of amino acids

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8
Q

What is each amino acids coded by

A

For by 3 bases in a gene called triplet or codon

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9
Q

How do you make polypeptide

A

DNA if first copied into messenger RNA, this is the first stage of protein synthesis

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10
Q

Genes that don’t code for polypeptide codes for what?

A

Functional RNA

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11
Q

What is functional RNA

A

RNA molecules other than mRNA which preform special tasks during protein synthesis

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12
Q

Give 2 examples of functional RNA

A

tRNA and rRNA

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13
Q

What is a genome

A

Full set of genes in a cell

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14
Q

What is proteome

A

Full range of proteins that the cell is able to produce

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15
Q

What are introns

A

Non-coding regions of DNA

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16
Q

When are introns removed

A

During protein synthesis

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17
Q

Why are introns removed during protein synthesis

A

So they don’t affect amino acid order

18
Q

What type of DNA doesn’t contain introns

A

Prokaryotic

19
Q

What are introns

A

Coding regions of DNA

20
Q

What are regions of multiple repeats

A

Sequence that repeats over and over again, they don’t code for AA either they are called non-coding multiple repeats

21
Q

What’s an allele

A

A different version of a gene

22
Q

How do chromosomes pair

A

In homologous pairs

23
Q

What are chromosomes like in homologous pairs

A

Same size and have the same genes, however they can have different alleles although alleles coding for the same will be found at the same fixed position (locus) on each chromosome

24
Q

What is protein synthesis

A

Production of proteins from the information contained within a cells DNA

25
Q

What’s the 2 stages of protein synthesis

A

Transcription and Translation

26
Q

What’s the structure of mRNA

A

Single polynucleotide strand

27
Q

Where is mRNA made and what does it do

A

Made during transcription it carries the genetic code from the DNA to ribosomes where it’s used to make a protein during translation

28
Q

What is tRNA involved in

A

Translation

29
Q

What does tRNA do

A

Carries AA that are used to make proteins to the ribosomes

30
Q

What’s the structure of tRNA

A

Single polynucleotide strand that’s folded into a clover shape, hydrogen bonds between specific base pairs hold the molecule in this shape
Every tRNA has a specific sequence of three bases at one end called an anticodon
It has an AA binding site at the other end

31
Q

What is step 1 of transcription

A

RNA polymerase attaches to the DNA, transcription starts when RNA polymerase attaches to the DNA double helix at the beginning of a gene
The hydrogen bonds between the two DNA strands break separating the strands and the DNA molecule uncoils exposing some of the bases
One is used to make a template

32
Q

What is step 2 of transcription

A

The RNA polymerase lines up free RNA nucleotides alongside exposes bases on the template stand
The free bases are attracted to the exposed bases, specific complementary base pairing means that mRNA strand is a complementary copy
Except T is replaced by U
Once paired RNA polymerase joins them up forming mRNA molecule

33
Q

What is step 3 of transcription

A

RNA polymerase moves along the DNA, separating the stands and assembling the mRNA stand
Hydrogen bonds between uncoiled strands reform once RNA polymerase has passed over them
Coiling back into a double-helix

34
Q

What is step 4 of transcription

A

When RNA polymerase reaches a particular sequence of DNA called stop signal it stops making the mRNA and detaches from DNA
mRNA moves out of the nucleus through a nuclear pore and attaches to a ribosome in cytoplasm where translation occurs

35
Q

What is meant by editing mRNA

A

In eukaryotes introns and exons are copied into the DNA mRNA containing both is called pre-mRNA, a process called splicing occurs where introns are removed and exons are joined together forming mRNA
Taking place in nucleus, RNA leaves nucleus for translation

36
Q

What’s step 1 of translation

A

mRNA attaches itself to a ribosomes and tRNA molecules carry AA to it, ATP provides the energy needed for the bond between AA and tRNA molecule to form

37
Q

What is step 2 of translation

A

A tRNA molecule (carrying AA) with an anti-codon that’s complementary to the first codon on the mRNA attaches itself to the mRNA by complementary base pairing
A second tRNA molecule attaches itself to the next codon on the mRNA in the same way

38
Q

What is step 3 of translation

A

The two AA attaches to the tRNA molecules are joined by a peptide bond
The first tRNA molecule moves away, leaving its AA behind

39
Q

What is step 4 of translation

A

Third tRNA molecule binds to the next codon on the mRNA
It’s AA binds to the first two and the second tRNA molecule moves away
This process continues producing a chain of linked AA until there’s a stop signal on the mRNA molecule
Polypeptide chain then moves away from the ribosomes and translation is complete

40
Q

What is the genetic code

A

Sequence of base triplets in mRNA which code for specific AA
In the genetic code each base is read in sequence, separate from triplet before it and after it

41
Q

What are the 3 main features of the genetic code (explained)

A

Non-overlapping: Base triplets don’t share their bases
Degenerate: there’s more possible combinations of triplets than there are AA meaning some AA are coded for by different combinations
Universal: same specific base triplets code for the same AA in all living things