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Human Biology Unit 1 > KA3 - Gene Expression > Flashcards

KA3 - Gene Expression Flashcards

1
Q

What is gene expression?

A

Gene expression involves the transcription and translation of DNA sequences

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2
Q

What is an RNA nucleotide composed of?

A

A ribose sugar

A phosphate group

One of the 4 bases (adenine, thymine, cytosine, guanine)

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3
Q

What are the 3 types of RNA?

A

mRNA (messenger RNA)

rRNA (ribosomal RNA)

tRNA (transfer RNA)

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4
Q

What is the function of mRNA?

A

mRNA is transcribed from DNA in the nucleus and translated into proteins by ribosomes in the cytoplasm

Each triplet of bases on the mRNA molecule is called a codon and codes for a specific amino acid

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5
Q

What is the function of rRNA?

A

rRNA, along with proteins forms the ribosome

The ribosome is the site of protein synthesis

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6
Q

Describe the structure of tRNA

A

tRNA has a folded shape due to complimentary base pairing

The bases of tRNA are held together by weak hydrogen bonds

A tRNA molecule has an anticodon(an exposed triplet of bases) at one end and an attachment side for a specific amino acid at the other end

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7
Q

What is the function of tRNA?

A

The role of tRNA is to carry its specific amino acid to the ribosome

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8
Q

Define protein synthesis

A

Protein synthesis is the process by which instructions from DNA sequences are carried to ribosomes and proteins are made.

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9
Q

What is the first stage of protein synthesis?

A

Transcription

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10
Q

What is transcription?

A

Transcription is the process by which mRNA is transcribed from DNA

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11
Q

What is the first stage of transcription?

A
  1. The enzyme RNA polymerase moves along DNA, unwinding the double helix and breaking the hydrogen bonds between the bases thereby unzipping the double helix
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12
Q

What is the second stage of transcription?

A
  1. As RNA polymerase breaks the bonds, it synthesises a primary transcript of mRNA on the DNA template strand using free RNA nucleotides. These RNA nucleotides form hydrogen bonds with the exposed DNA bases by complimentary base pairing
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13
Q

What is the third stage of transcription?

A
  1. A primary mRNA transcript is formed
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14
Q

What two components is the primary transcript made of?

A

Introns and exons

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15
Q

What are introns?

A

Introns are regions of the primary transcript of mRNA which are non-coding

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16
Q

What are exons?

A

Exons are coding regions of the primary transcript of mRNA

17
Q

What happens during splicing?

A

The introns are removed from the primary transcript

The exons are then joined together to form the mature transcript

18
Q

What is the mature transcript?

A

The mature transcript leaves the nucleus through a pore in the nuclear membrane

The mature transcript travels through the cytoplasm to a ribosome for the next stage of protein synthesis

19
Q

What is the second stage of protein synthesis?

A

Translation

20
Q

What is translation?

A

Translation is the synthesis of a polypeptide chain under the direction of mRNA at the ribosome

21
Q

What happens during translation?

A

Translation begins at a start codon and ends at a stop codon

Anti codons bond to codons by complimentary base pairing, translating the genetic code into a sequence of amino acids

Peptide bonds join the amino acids together

Each tRNA then leaves the ribosome as the polypeptide is formed

tRNA has an anticodon and amino acid attachment side

22
Q

What can happen as a result of alternative RNA splicing?

A

Different proteins can be expressed from one gene, as a result of alternative RNA splicing

23
Q

What happens depending on which exons are retained?

A

Different mature mRNA transcripts are produced from the same primary transcript depending on which exons are reatined

24
Q

What are amino acids linked by and what does this form?

A

Amino acids are linked by peptide bonds to form polypeptides

25
Q

What do polypeptide chains fold to form?

A

Polypeptide chains fold to form the three dimensional shape of a protein, held together by hydrogen bonds and other interactions between individual amino acids

26
Q

What determines a proteins function?

A

Proteins have a large variety of shapes which determine their functions

27
Q

What is phenotype determined by?

A

Phenotype is determined by the proteins produced as the result of gene expression

Human Biology Unit 1 (8 decks)

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