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Biology A level > Cellular control > Flashcards

Cellular control Flashcards

1
Q

What are gene mutations

A

Random alteration in the nucleotide sequence of a cell of a living organism

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2
Q

What are point mutations

A

Changes in an individual gene due to miscopying of one or more nucleotides. They occur at a single point in a sequence
There can be more than one point mutation in a sequence

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3
Q

What are the types of point mutation

A

Substitution, Insertion and Deletion mutations

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4
Q

What are substitution mutation

A

The change of one base - resulting in one triplet code

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5
Q

What are insertion mutations

A

When a new base is inserted into DNA base sequence
Changes the triplet code at the point of mutation - causes a frameshift effect

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6
Q

What are deletion mutations

A

When a random base is deleted from the nucleotide base sequence
They change triplet code at point of mutation, but also have a frameshift effect

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7
Q

What are the three types of substitution mutations

A

Silent
Nonsense
Missense

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8
Q

What are silent mutations

A

Substitution of a base still codes for original amino acid - possible due to the degenerate nature of the genetic code
no effect

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9
Q

What is a nonsense mutation

A

Premature stop codon is being coded for
Unlikely that final protein would be able to function normally

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10
Q

What is Thalassemia an example of and what are some of its features

A

Nonsense mutation, sufferers have no synthesis of a beta chain that makes up haemoglobin

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11
Q

What is a missense mutation

A

A single amino acid is different in final polypeptide, effect can vary depending on role of original amino acid

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12
Q

What is sickle cell disease and example of

A

A missense mutation causes the RBC to have a distorted shape

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13
Q

What is the Lac Operon

A

A group of three genes involved in the metabolism of lactose

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14
Q

What does LacI encode for

A

repressor protein

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15
Q

What does LacO do

A

it is the operator region of the DNA

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16
Q

What does LacZ encode for

A

B-galactosidase

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17
Q

What does LacY encode for

A

permease proteins

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18
Q

What does LacA encode for

A

B-galactosidase transacetylase - adds an acetyl group to B-galactosidase

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19
Q

How is Repressor protein made

A

RNA polymerase binds to promotor region of regulatory gene, transcribing the LacI
mRNA is translated by ribosomes to produce a repressor protein that has two binding sites (Lactose, LacO)

20
Q

What happens when Lactose is absent

A

Repressor protein binds to LacO, blocking promotor region so that RNA cannot bind to it and the structural genes cannot be transcribed
This means no B-galactosidase is made and no lactose is broken down

21
Q

What does lactose permease do

A

transport lactose into the cell

22
Q

What does B-galactosidase do

A

Catalyses hydrolysis of lactose into glucose and galactose

23
Q

What happens when lactose is present

A

Lactose binds to the binding site on repressor protein, changing the shape so that it cannot bind to LacO
This allows RNA polymerase to bind to LacP so that the structural genes can be transcribe and B-galactosidase is made

24
Q

Why is lactose called an inducer

A

It induces the transcription of the enzymes that break it down

25
Q

How are genes expressed in eukaryotes

A

They have cells that have different sections of the DNA switched on or off

26
Q

What are transcription factors

A

Proteins or non-coding pieces of RNA that work within the nucleus to control the expression of genes
They bind to their specific promotor region to repress or activate transcription

27
Q

What is splicing

A

The post transcriptional process of removing non-coding RNA from the strand befroe translation

28
Q

What are coding DNA called

A

Exons

29
Q

What is non-coding DNA called

A

Introns

30
Q

Why is alternative splicing beneficial

A

More than one protein can be coded from one gene

31
Q

What happens during splicing

A

Introns are removed from the mRNA

32
Q

What is a kinase

A

An enzyme that catalyses the transfer of phosphate groups from ATP to specific substrates
eg. catalyses phosphorylation

33
Q

What are homeobox genes

A

A group of genes containing homeobox that code for protein transcription factors

34
Q

How long are homeobox genes

A

180 base pairs long

35
Q

Why are homeobox genes similar in plants, animals and fungi

A

Highly conserved, so they have been unchanged by natural selection

36
Q

What is the role of homeobox genes

A

Responsible for the genetic control of the development of body parts
They help form basic pattern of the body and control segmentation

37
Q

What are hox genes

A

Subsection of homeobox genes that only exist in animals

38
Q

What is the role of hox genes

A

Determine positioning of body parts

39
Q

Features of hox genes

A

In groups called hox clusters
Vertebrates have 4 clusters
There is a linear order to hox genes that relate to the order of regions they effect

40
Q

What does diploblastic mean

A

2 primary tissue layers

41
Q

What does triploblastic mean

A

3 primary tissue layers

42
Q

What is radial symmetry

A

No left + right, only a top and a bottom
(jellyfish)

43
Q

What is bilateral symmetry

A

Left + right sides, top and a bottom

44
Q

What is the role of mitosis and apoptosis in forming an organism

A

Shape + sculpt organisms
Apoptosis release chemical signals to stimulate mitosis

45
Q

What is the process of apoptosis

A

Nucleus condenses, cell shrinkage and blebs form
Nucleus fragments and apoptotic bodies form
Apoptotic bodies are engulfed by phagocytes

46
Q

What is epigenetics

A

the study of how cells control gene activity without changing the DNA sequence

47
Q

What factors affect regulatory gene expression

A

stress
temp
light
hormones
drugs

Biology A level (20 decks)

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