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A2 OCR Biology > cellular control from book (Dixon) > Flashcards

cellular control from book (Dixon) Flashcards

1
Q

Define gene

A

Section of DNA that codes for a characteristic

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2
Q

Define allele

A

Different versions of the same gene

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3
Q

Define DNA

A

Genetic material

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4
Q

Define phenotype

A

Characteristic that is expresed

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5
Q

Define genotype

A

Combinations of alleles

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6
Q

Define homozygous

A

2 of the same alleles

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7
Q

Define heteozygous

A

2 different alleles

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8
Q

Define mutation

A

A change in the DNA

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9
Q

Define dominant

A

The gene that is expressed if it is there

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10
Q

Define recessive

A

Have to have both alleles recessive for the characteristic to be expressed.

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11
Q

What are the 5 possible bases for a nucleotide?

A 
Adenine
Thyamine
Guanine
Cytosine
Urasil
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12
Q

What are the 2 types of bases?

A

Purine - 2 carbon- nitrogen hexagonal rings (A+G)

Pyramidine- 1 carbon- nitrogen hexagonal ring (T,C +U)

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13
Q

What are the 3 types of RNA?

A

mRNA
rRNA
tRNA

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14
Q

Define triplet

A

Sequence of 3 bases (codon) that codes for a specific amino acid.

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15
Q

How is the genetic code non-overlapping?

A

The bases are read in sequence and triplets do not share bases.

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16
Q

How is the genetic code degenerate?

A

More than one combination of bases can code for the same amino acid.

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17
Q

How is the gentic code universal?

A

The same triplet codes for the same amino acid in all living things.

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18
Q

Define transcription

A

The coping of a section of DNA that codes for a protein to form mRNA.

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19
Q

Describe the process of transcription

A

DNA is untwisted
DNA unzips by DNA helicase
This breaks hydrogen bonds
One side is used as a template
Free RNA nucleotides attach to exposed bases
Due to complementary base pairing A with U, C with G
Temporary hydrogen bonds form
RNA polymerase catalyses bond formation of phosphodiester bonds between adjacent RNA nucleotide
Single strand of mRNA produced
mRNA moves out of the nucleus

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20
Q

What is the template strand of DNA?

A

What the mRNA attaches to

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21
Q

What in the coding strand of DNA?

A

The same as the mRNA

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22
Q

Describe the process of translation

A

1) mRNA attaches to ribosome
2) The tRNA anticodon binds to complementary mRNA codon
3) Each tRNA brings a specific amino acid
4) A second tRNA brings a second specific amino acid
5) Peptide bond formed between amino acids
6) This is catalysed by the ribosome
7) The first tRNA detaches
8) Ribsome moves along the mRNA
9) Polypeptide chain grows as steps 2-8 continue
10) This process halts when a stop codon is reached.
11) Ribosome detaches from mRNA.

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23
Q

What is a mutation?

A

A random change in the genetic material (DNA)

It can occur at any point in the DNA - the genes, the regulatory regions the non-coding DNA.

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24
Q

What is a polymer?

A

A long chain of monomers

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25
Q

What is the primary structure of a protein?

A

Long chain of amino aicds held together by peptide bonds

26
Q

What are the 2 types of mutation?

A

Point mutation and indel mutation

27
Q

What is a point mutation?

A

Where 1 base pair is substituted by another

28
Q

What is an indel mutation?

A

Insertion of base pairs or deletion of base pairs.

29
Q

What is a silent point mutation?

A

The change in the order of the bases still codes for the same amino acid so there is no effect in the protein produced.

30
Q

What is a missense point mutation?

A

The change in the order of bases codes for a different amino acid so this affects the primary structure of the polypeptide and the tertiary structure.

31
Q

What is a nonsense point mutation?

A

The change in the order of bases causes the triplet to become a STOP codon. This means the polypeptide is shorter than it should be, the right bonds will not form, the correct shape will not be acheived and the protein will not function.

32
Q

What is an indel causing frame shifts mutation?

A

These are mutations caused by the insertion or deletion of base pairs. Insertions and deleations can cause frame shifts. This can be the insertion or deletion of one or more bases (not in 3s).

33
Q

What is an indel without framshift mutation?

A

These are mutations caused by the insetion or deletion of base pairs. This is insertion in 3s so it does not cause a frame shift.

34
Q

What mutation causes sickel cell anaemia?

A

Missence mutations

35
Q

What is an operon?

A

A group of structural genes with control elements (and sometimes regulatory genes)

36
Q

What does E.coli respire with if there is no glucose?

37
Q

What enzymes are needed for E.coli to respire lactose?

A

Lactose permease and B-galactosidase

38
Q

What is the function of lactose permease?

A

Lets lactose into cells

39
Q

What is the function of B-galactosidase?

A

Hydrolyses lactose to glucose and galactose.

40
Q

When is lactose permease and B-galactosidase produced?

A

When lactose is present

41
Q

In the DNA what are 2 structural genes?

A

Lac Z and Lac Y

42
Q

What does Lac Z code for?

A

B-Galactosidase

43
Q

What does Lac Y code for?

A

Lactose permease

44
Q

What are the control sites on a lac operon?

A

Lac O and P

45
Q

What is lac O?

A

It is the operator region which turns the genes on or off

46
Q

What is lac P?

A

It is the promoter region where RNA polymerase attaches to the DNA for transcription

47
Q

What does the regulatory gene do?

A

This codes for a repressor protein which binds to the operator site (lac O). When this happens the RNA polymerase cannot bind.

48
Q

What happens to prokaryotes if glucose is present?

A 
Lac Z is not transcribed
Repressor protein is correctly shaped
RNA polymerase cannot bind to P
Lactose permease is not produced
B-galactosidase is not produced
Lac Y is not transcribed
49
Q

What happens in prokaryotes if glucose is not present?

A 
Lac Z is transcribed 
Repressor protein is deformed
RNA polymerase can bind to P
Lactose permease is produced
B-galactosidase is produced
Lac Y is transcribed
50
Q

What are transcription factors?

A

These are proteins or small, non-coding sections of RNA.

51
Q

How does a transcription factor turn on a gene?

A

1) They bind to specific promoter regions on the DNA near to the start of their target cells
2) They aid the attachment of RNA polymerase to the DNA
3) Transcription of the gene is activated
4) The gene is expressed

52
Q

How does a transcription factor turn off a gene?

A

1) They bind to specific promotor regions on the DNA near to the start of their target cells
2) They inhibit the attachment of RNA polymerase to the DNA
3) Transcription of the gene is supressed
4) The gene is not expressed.

53
Q

Where are transcription factors found?

A

In the nucleus of the cell

54
Q

What are transcription factors used for?

A

They are essential for regulatig gene expression in eukaryotes. They are also used in cell differentiation and reglating the cell cycle.

55
Q

How can some transcription factors be altered?

A

Other molecules binding to them, e.g. hormones

56
Q

What are introns?

A

Non-coding regions of DNA

57
Q

What are exons?

A

Coding regions of DNA

58
Q

How is primary mRNA produced?

A

The whole gene is transcribed (introns and exons)

59
Q

How is mature mRNA produced?

A

The primary mRNA is edited and the introns removed. (This may involve endonuclease).

60
Q

What happens to introns?

A

Some may become transcription factors, Some may code for proteins.

61
Q

How can 1 gene code for multiple proteins?

A

Genes can be spliced (joined) in different ways.

A2 OCR Biology (6 decks)

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