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genetic info, variation and relationships between organisms > DNA, genes and protein synthesis > Flashcards

DNA, genes and protein synthesis Flashcards

1
Q

what is a gene?

A

A gene is a section of DNA that contains the coded information for making polypeptides and functional RNA.

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2
Q

What is the locus?

A

A locus is the position of a gene on a chromosome

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3
Q

What factors determine the nature and development of all organisms?

A

Genes and environmental factors

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4
Q

The genetic code uses 4 different DNA bases. What is the maximum number of different DNA triplets that can be made from these 4 bases?

A

4^3 = 64

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5
Q

What are some of the features of genetic code?

A

•It’s degenerative •It’s non-overlapping (each base only ready once) •It’s universal

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6
Q

Why is genetic code described as “degenerative”?

A

As one amino acid can be coded for by more than one triplet

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7
Q

Why is the genetic code described as being “universal”?

A

In all organisms the same triplet codes for the same amino acid;

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8
Q

What are exons?

A

Sequence that codes for amino acids.

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9
Q

What are introns?

A

Non-coding sequences (not ITNRested in them)

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10
Q

Why is the genetic code described as “non-overlapping”?

A

Each base in the sequence is only read once

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11
Q

Describe the DNA in prokaryotic cells

A

•DNA molecules are shorter •They form a circle •They aren’t associated with proteins (histones) •NO chromosomes

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12
Q

Describe the DNA in eukaryotic cells

A

•DNA molecules are longer •They form a line (linear) •They occur in association with proteins called HISTONES to form chromosomes

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13
Q

What is an allele?

A

Different form of a gene

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14
Q

Explain why the DNA base sequences of homologous chromosomes are almost the same.

A

Homologous chromosomes have the same genes At the same loci Different alleles (different forms of the same gene) usually only have a small difference in their base sequence

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15
Q

What name is given to the different forms of a gene?

A

Allele

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16
Q

Which 2 biological molecules make up a ribosome?

A

ribosomal RNA (rRNA) and Amino acids

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17
Q

Describe the shape of a replicated chromosome

A

X shape - sister chromatids

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18
Q

name the enzyme involved in DNA replication

A

DNA polymerase

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19
Q

What is a homologous pair of chromosomes?

A

Two chromosomes in a pair – normally one inherited from the mother and one from the father.

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20
Q

Define genome

A

complete set of genes in the cell

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21
Q

Define proteome

A

The full range of proteins that a cell can make

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22
Q

Define codon

A

Three bases on mRNA that code for an amino acid

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23
Q

Define anti-codon

A

Three bases on tRNA that are complementary to the codon on mRNA

24
Q

Name the process that removes base sequences from pre-mRNA to form mRNA.

A

Splicing

25
Q

Give some ways in which the structure of an mRNA molecule is different from the structure of a tRNA molecule.

A
  • mRNA is a single helix where as tRNA is a clover shaped molecule
  • mRNA do not contain hydrogen bond where as tRNA do
  • mRNA do not have base pairing where as tRNA do
  • mRNA has codons where as tRNA has anti-codons
  • mRNA don’t have an amino acid binding site where as tRNA do
26
Q

Explain the difference between pre-mRNA and mRNA.

A
  1. Pre-mRNA contains introns where as mRNA contains only exons;
  2. mRNA has undergone splicing, pre-mRNA has not.
27
Q

What is the role of RNA polymerase during transcription?

A

To join RNA nucleotides together (by forming phosphodiester bonds) to form mRNA

28
Q

Name the three steps involved in protein synthesis

A

Transcription
Splicing
Translation

29
Q

Describe how mRNA is produced in the nucleus of a cell.

A
  1. DNA helicase breaks the hydrogen bonds holding complementary base pairs
  2. One DNA strand acts as a template
  3. Free RNA nucleotides are attracted to DNA template strand.
  4. RNA nucleotides bind to their complementary base pair on the template strand - A>U; C>G
  5. RNA polymerase joins RNA nucleotides together
  6. Pre-mRNA is spliced to remove the introns
30
Q

Explain the role of the anticodon in protein synthesis.

A

Anticodons on the tRNA bind to codons on the mRNA
Anticodons are complementary to those on the codon
So the correct amino acid is brought to the ribosome

31
Q

Name the organelle involved in translation.

A

Ribosomes

32
Q

Describe the role of tRNA in the process of translation.

A
  1. Anticodons on tRNA are complementary to specific codons on mRNA
  2. A specific amino acid is bound to the tRNA
  3. This amino acid is carried to the ribosome
  4. Ribosome moves along mRNA.
  5. Peptide bond forms between adjacent amino acids.
  6. Via condensation reaction
  7. Requires ATP.
  8. Ribosome detaches from mRNA when STOP codon reached.
33
Q

Starting with mRNA, describe how the process of translation leads to the production of a polypeptide.

A
  1. The mRNA attaches to a ribosome
  2. Anticodons on tRNA are complementary to specific 3. codons on mRNA
  3. A specific amino acid is bound to the tRNA
  4. This amino acid is carried to the ribosome
  5. Ribosome moves along mRNA.
  6. Peptide bond forms between adjacent amino acids.
  7. Via condensation reaction
  8. Requires ATP.
  9. Ribosome detaches from mRNA when STOP codon reached.
34
Q

What is a histone?

A

A protein that DNA forms a complex with to allow it to be condensed into a chromosome.

35
Q

When chromosomes become visible at the start of cell division, they appear as 2 threads joined at a central point called a…

A

centromere

36
Q

The 2 condensed ‘threads’ of DNA that are joined at a centromere and make up a chromosome are called…

A
37
Q

Describe how DNA is packed into a chromosome.

A
38
Q

What is meant by homologous chromosomes?

A
39
Q

The total number of maternal AND paternal chromosomes in an organism is called its…

A
40
Q

If a tRNA is involved what stage of protein synthesis are we looking at?

A
41
Q

what shape does a tRNA have?

A
42
Q

The codon on mRNA is AUG - what will be the complementary DNA and anti-codon?

A
43
Q

How do new alleles come about?

A
44
Q

Do homologous chromosomes carry the same alleles (version of genes)?

A
45
Q

define allele

A
46
Q

How do new alleles come about?

A
47
Q

How are DNA nucleotides different to RNA nucleotides?

A
48
Q

How is mRNA structure different to tRNA?

A
49
Q

Describe how mRNA is made in the nucleus

A
50
Q

name the 3 bases in mRNA that codes for a specific amino acid

A
51
Q

Describe the role of the ribosome in the production of a polypeptide

A
52
Q

The base sequence of mRNA maybe different the sequence of pre-mRNA in eukaryotic cells

A
53
Q

define degenerate

A
54
Q

describe how mRNA differs to tRNA

A
55
Q

Describe translation

A

genetic info, variation and relationships between organisms (3 decks)

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