Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A Level Biology : Content > Topic 3C : Differentiation & Variation > Flashcards

Topic 3C : Differentiation & Variation Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

what are the two epigenetic controls that determine whether certain genes are expressed

A

methylation of DNA

histones modification

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

methylation of DNA

A

methyl group attached at CpG site where a cytosine and guanine bases are next to each other in the DNA

increased methylation changes the DNA structure so proteins and enzymes needed for transcription cant bind to the gene and gene is not expressed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

histone modification

A

when histones are acetylated, the chromatin is less condensed so proteins involved in transcription can bind to DNA allowing genes to be transcribed

when acetyl groups are removed from histones, chromatin becomes highly condensed and genes in the DNA cant be transcribed as proteins cant bind (gene repressed)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is meant by epigenetics

A

a heritable change in gene function without changing the base sequence of DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

how are epigenetic changes passed on

A

because the changes affect cell division, all cells that arise from altered cells will possess the changes including gametes meaning that changes are heritao

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

give examples of continuous variation

A

height

mass

skin colour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

continuous variation

A

when individuals in a population vary within a range

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

discontinuos variation

A

when there are two ir more distinct categories and each individual falls in only one of them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

give example of discontinuos variation

A

blood group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

regulatory authorities

A

authorities established to consider benefits and ethical issues surrounding embryonic stem cell research

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

give three ways in which regulatory authorities help society consider the benefits and ethical issues of embryonic stem cell research

A

they look at proposals and decide if they should be allowed (taking ethical issues into account) so any research involving embryos is for a good reason.

licensing snd monitoring centres ensuring fully trained staff carry out the research as they will understand the implications of the research and wont waster any resources (avoid unregulated research).

producing guidelines and codes of practice ensuring all workers work in the same manner.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

state how stem cells can be used to treat a range of diseases

A

they can develop into any specialised cell types so scientists could use them to replace damaged tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

potential benefits of stem cell therapies

A

they could save many lives eg they could be used to grow organs for those waiting for transplants

they could improve the quality of life

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

name the two potential sources of human stem cells

A

adult stem cells

embryonic stem cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

from where are adult stem cells obtained

A

body tissues of adult eg bone marrow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

describe the operation that takes place to obtain adult stem cells

A

donor is anaesthetised and needle is inserted in the centre of the bone (usually the hip) and small quantity of bone marrow is removed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

limitations of adult stem cells

A

not as flexible, develop into a limited range of cells

operation causes a lot of discomfort

18
Q

where from are embryonic stem cells obtained

A

early embryos

19
Q

approximately when are stem cells removed from an embryo

A

4 to 5 days

20
Q

state an ethical issue in relation to embryonic stem cells

A

at the moment of fertilisation a genetically unique individual is formed that has the right to live

21
Q

transcription factors

A

proteins that bind to DNA and activate or deactivate genes by increasing or decreasing the rate of transcription

22
Q

activators

A

factors increasing the rate of transcription

23
Q

repressors

A

factors that decrease the rate of transcription

24
Q

operon

A

section of DNA that contains a cluster of structural genes that are transcribed together, as well as control elements and sometimes a regulatory gene

25
Q

control elements

A

promoter and operator

26
Q

promoter

A

a DNA sequence located before the structural genes that RNA polymerase binds to

27
Q

operator

A

a DNA sequence that transcription factors bind to

28
Q

lac operon

A

the location of the gene that produces the enzymes needed to respire lactose

29
Q

what are the lac operon structural genes

A

lacZ

lacY

lacA

30
Q

what proteins to the structural genes of the lac operon produce to help bacteria digest lactose

A

beta galactosidase

lactose permease

31
Q

describe what happens when lactose is not present

A

the regulatory gene (lacl) produces a repressor which is a transcription factor that binds to the operator site when no lactose is present blocking transcription ad RNA polymerase can’t bind to the promoter

32
Q

describe what happens when lactose is present

A

lactose binds to the repressor changing its shape so that it can no longer bind to the operator site leading to RNA polymerase starting transcription of the structural genes

33
Q

stem cells

A

unspecialised cells that can differentiate into other types of cells

34
Q

potency

A

the ability of stem cells to differentiate into specialised cells

35
Q

totipotency

A

the ability to produce all cell types including all the specialised cells in an organism and extraembryonic cells

36
Q

pluripotency

A

the ability of a stem cell to produce all the specialised cells in an organism but not extraembryonic

37
Q

explain why some cells do not remain totipotent

A

during fertilisation and after the first few cell divisions they become pluripotent and can specialise into any cell but not those that make up the placenta and the umbilical cord

38
Q

where in plants can you find stem cells

A

where the plants is growing eg roots and shoots

39
Q

describe how stem cells become specialised through differential gene expression

A

stem cells contain the same genes but not all are expressed as they are not active

under right conditions, genes are activated and others are inactivated

mRNA only transcribed from the active genes and is then translated into proteins which modify the cell eg cell structure and control cell processes

such changed cause the cell to become specialised which ate also difficult to reverse

40
Q

explain how the potency of plant cells is different from animal cells

A

in animal cells, once specialised, they are usually permanently specialised

however, in plant cells, they become specialised and unspecialised throughout their lifetime

41
Q

state 3 dangers of stem cell therapy

A

stem cells becoming cancerous

body may reject stem cells

when injecting stem cells, there is a risk of introducing an infection

42
Q

phenotype

A

the expression of an organism’s genes combined with its interaction with the environment

A Level Biology : Content (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions