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Biology Edexcel A Alevel > Topic 3 > Flashcards

Topic 3 Flashcards

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1
Q

what are all organisms made up of?

A

cells

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2
Q

what makes the spindle during nuclear division

A

centrioles

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3
Q

where do the later stages of aerobic respiration takes place

A

mitochondria

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4
Q

what controls the synthesis of proteins

A

nucleus

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5
Q

what does the nucleus contain

A

nucleolus and chromosomes

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6
Q

where are ribosomes made

A

nucleolus

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7
Q

where are the proteins made

A

Rough ER

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8
Q

what are ribosomes made up of

A

RNA and proteins

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9
Q

where does protein synthesis take place

A

ribosomes

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10
Q

what makes up the cell surface membrane

A

phospholipid bilayer

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11
Q

what does the smooth ER make

A

lipids and steroids

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12
Q

what does the Golgi apparatus do?

A

modifies proteins and packages them in vesicles for transport

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13
Q

what do lysosomes contain

A

digestive enzymes

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14
Q

what do lysosomes do?

A

breakdown old cells needed to be replaced

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15
Q

what are the 8 steps of protein synthesis

A
  1. DNA transcribed to mRNA
  2. mRNA leaves nucleus
  3. proteins make on ribosomes enter rough ER
  4. proteins move through ER forming 3D shape
  5. vesicle pinched off rough ER contains protein
  6. vesicle fuses into Golgi apparatus
  7. proteins modified in Golgi
  8. vesicle pinched with modified protein
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16
Q

where does respiration take place in prokaryotic cells

A

cell surface membrane infolding

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17
Q

what is a plasmid

A

a small circle of DNA

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18
Q

what does the capsule do

A

slimy layer that protects and prevents dehydration

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19
Q

what do the pili do

A

allow bacteria to adhere to surfaces

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20
Q

what is the structure of pili and what is it made up

A

thin protein tubes

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21
Q

what do the flagellum do

A

move the cell

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22
Q

what does the cell wall contain

A

peptoglycan

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23
Q

where does protein production take place

A

ribosomes

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24
Q

how does the ovum move

A

wafted along the oviducts by ciliated cells and muscular contractions of the tubes

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25
Q

how is the sperm cell specialised for movement

A

flagellum power by energy released from mitochondria

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26
Q

what is the role of the acrosome and how is it specialised

A

the acrosome swells and suddenly fuses with the sperm cell surface membrane and releases digestive enzymes which break down the zona pellucida

27
Q

what is the acrosome a type of

A

a type of lysosome- enzyme filled sacs

28
Q

how is the zona pellucida specialised

A

sperm fuses and penetrates cell membrane ZP thickens preventing any further sperm

29
Q

what is it called when the zona pellucida hardens

A

cortical reaction

30
Q

what happens in the acrosome reaction

A

acrosome swells fuses with cell surface membrane acrosome releases digestive enzymes enzymes break down zona pellucida

31
Q

what happens once the sperm reaches the egg nucleus

A

a. sperm haploid nucleus fuses with egg haploid nucleus to produce a fertilised egg (zygote)

32
Q

What is the loci (locus)

A

Location of a gene on a chromosome

33
Q

Why might some genes be more likely to be found together than others

A

the locus of the genes on the same chromosome that are closer together are more likely to be passed down together as crossing over between the two is very unlikely

34
Q

Why do some genetic conditions occur in men more often than women

A

As for males if the locus of the gene is higher on the X chromosome then it will not be blocked by the Y chromosome whereas in women if it’s recessive it requires both the mother and father to pass it down for the phenotype to occur

35
Q

What happens before division in meiosis

A

chromosomes replicate before division

36
Q

What is found before replication in meiosis

A

Homologous pair of chromosomes

37
Q

what is each chromosome made up of after replication

A

two chromatids

38
Q

What happens in meiosis 1

A

Homologous chromosomes pair up separately

39
Q

What happens in meiosis 2

A

Second division splitting of chromatids

40
Q

What is independent assortment

A

the chromosomes pairs randomly line up before the first stage of meiosis

41
Q

What is crossing over

A

during first meiotic division the homologous pairs come together and all for chromatids come into contact. At contact point they break and join exchanging sections of DNA.

42
Q

What is where chromosomes break called

A

Chiasma

43
Q

what are the 3 stages of mitosis

A

prophase, metaphase, anaphase and telophase

44
Q

what happens in prophase

A

chromosomes condense, becoming shorted and thicker spindles form and chromosomes move to equator

45
Q

what happens in metaphase

A

chromosomes centromeres attach to spindle fibres

46
Q

what happens in anaphase

A

centromeres split and spindle fibres shorten pulling the two halves in opposite directions towards the poles

47
Q

What happens in telophase?

A

chromosomes unravel and are enclosed in a separate nuclear envelope

48
Q

what is meant by stem cells

A

cells from which all other cells are specialised

49
Q

what is meant by pluripotent

A

can give rise to most cell types but not all cells that makeup the human body

50
Q

what is meant by totipotency

A

totipotent cells can develop into all types of cells in a complete human

51
Q

how do genes become specialised through gene expression

A

specialised cells are only expressing some of their genes as only specific proteins are being synthesised

52
Q

what happens in the lac operon model when lactose is absent

A

RNA polymerase cannot bind a repressor molecule is blocking the operator so B-galactosidase cannot be produced

53
Q

what happens in the lac operon model when lactose is present

A

lactose binds to the repressor gene inactivating it RNA polymerase can bind so mRNA coding for B-galactosidase is produced B-galactosidase enzyme digests lactose resulting in the repressor binding again

54
Q

what is a cell

A

in multicellular organisms cells are specialised for a particular function

55
Q

what is a tissue

A

a group of specialised cells working together to carry out a particular function

56
Q

what is an organ

A

group of tissues working together to carry out one function

57
Q

what is the phenotype a result of

A

a reaction between genotype and environment

58
Q

what is the epigenome

A

influences which genes can be transcribed in a particular cell

59
Q

what happens if DNA methylation increases

A

methyl group attaches to DNA preventing transcription any further

60
Q

what does the acetyl group do

A

the addition of an acetyl group to the histone tail causes the DNA to wrap less tightly around the histone

61
Q

How can epigenetic changes be passed on after cell division?

A

the histones are copied along with the DNA

62
Q

what is meant by polygenic inheritance

A

when a number of genes are involved in the inheritance of a characteristic

63
Q

what is meant by multifactorial inheritance

A

when conditions of several genetic factors and one or more environmental factors are involved

Biology Edexcel A Alevel (15 decks)

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