Cell control Flashcards

1
Q

what is apoptosis

A

programmed cell death

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2
Q

how is apoptosis controlled

A

intrinsic and extrinstic inducers, depends on balance between positive and negative signals

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3
Q

intrinsic inducer

A

intracellular signals- hormones que stim mitosis, DNA damage distrupting cell cycle

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4
Q

extrinsic inducer

A

extracellular signals- nutrient stress in a cell, viral infection

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5
Q

role of apoptosis in morphogenesis

A

as mitosis and cell diff create bulk of body parts
apop refines parts by removing unwanted sturctures
e.g. spacing the nerve cells in CNS

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6
Q

where does apoptosis occur

A

multicellular organisms

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7
Q

describe the process of apoptosis

A

cell shrinkage
DNA and protein degraded
c.m. blebs, chromatin condensation, discontinuous nuc env, cell breaks apart into apoptotic bodies which are phagocytosed along w/blebs by mac

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8
Q

why do cells commit suicide

A

part of body’s defence against pathogens/ dangerous, damaged cells
part of the normal developmental process for the organism

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9
Q

what process has a similar biochemical pathway to apoptosis

A

cell division

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10
Q

similarities between apoptosis and mitosis

A

similar biochemical pathways
tightly controlled
both tiggered by internal and external factors

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11
Q

what is morphogenesis

A

shaping of the organism and its parts

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12
Q

when does morphogenesis and cell differentiation occur in animals, plants and fungi

A

animals- mainly during embryonic stage

plants and fungi- continually

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13
Q

what are homebox genes

A

DNA seqs que contain a homebox seq and inv in reg of patterns of dev and cell diff in animals, plants and fungi

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14
Q

how are homebox genes expressed

A

in specific patterns at particular stages of the organism’s dev

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15
Q

what do regulatory/ homeotic genes contain

A

a homebox seq (180 base pairs) that code for a homeodomain

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16
Q

what do regulatory/ homeotic genes contain

A

a homebox seq (180 base pairs which code for 60 a.a) that code for a homeodomain

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17
Q

how many other genes can 1 homeobox gene switch on

A

many other genes

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18
Q

state a characteristic of homeobox genes

A

highly conserved

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19
Q

state a characteristic of homeobox genes

A

highly conserved in evolution

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20
Q

what is the name for the type of homebox gene that animals have

A

hox genes

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21
Q

what are the role of hox genes

A

control body plan development in animals- correct positioning of body parts

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22
Q

what is plants and animals morphology usually governed by

A

environmental factors

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23
Q

in what way are homebox genes conserevd in evolution

A

the homebox DNA seq evolved at early stage in history of life can be seen in distantly related eukaryotes

24
Q

how many hox box gene clusters are in humans (vertabrates)

A

4, on different chromosomes

25
Q

why are homebox genes said to be highly conserved

A

little variation in the DNA sequence

26
Q

what do hox genes code for

A

proteins that act as transcription factors

27
Q

what does the presence of transcription factors mean

A

genes can be repressed or activated

28
Q

the order of hox genes along the chromosome corresponds to…

A

the order the hox genes are expressed

29
Q

what might be the result of an increased number of hox genes

A

greater complexity in body structure

30
Q

how did hox genes arise

A

gene duplication

31
Q

what may have been a critical event in the formation of body plans

A

genetic variation

32
Q

what about hox genes varies between diff types of animals

A

number and arrangement

33
Q

function of homebox genes

A

contolling the development of the organism’s body and ensure structures develop n the correct positions

34
Q

structure of homebox gene

A

180 base pairs long

35
Q

what do homebox genes encode

A

polypeptide sequences that are 60 amino acids long- homeodomains

36
Q

homedomain

A

transcriptional factors that bind to DNA and switch genes on or off

37
Q

examples of dev rols played by homebox genes

A

deterination of tail and head of an org and reg balance bw apop and mtiosis

38
Q

how do homeobox genes differ bw species

A

different numbers of homebox genes

39
Q

suggest why vertabrates have more homeobox genes than invert

A

.

40
Q

explain how hox genes can cause diff of cells

A

.

41
Q

point mutation

A

change in a single nucleotide

42
Q

substitution

A

1 or more nucleotides replaced

43
Q

insersion

A

addtion os bases

44
Q

deletion

A

removal of bases

45
Q

possible effects of substitution on protein sturcture and function

A

change in primary sturcutre

neutral due to degenerate nature of genetic code

46
Q

poss eff of ins/del on stuc and finc of proteins

A

frameshift, moving reading frame of seq
incorr bases read
changes every codn after point of mutation

47
Q

when does del/ins not res in frame shift, eff on protein

A

if multiples of 3 as correspond w/

protin formed still aff as new aa added

48
Q

eff of diff mutaions

A

neutral- no eff on p.type
benficial- useful chara
harmful- intefre w/ essential processes

49
Q

when do mutations often occur

A

DNA rep in somatic cells

50
Q

what increases the rate of mutations

A

mutagens

51
Q

silent mutations

A

neutra, in introns, incl del/ins

52
Q

nonsense

A

codon becoming stop codon instead of aa, prod shortened protein

53
Q

transcriptional level

A

alter conditions to allow RNA polymerase to bind

54
Q

post-translational level

A

modifying the polypeptides to mke proteins of specific functions

55
Q

post-transcriptional level

A

.