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Biology Edexcel A Alevel > Topic 3 > Flashcards

Topic 3 Flashcards

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
how is the sperm cell specialised for movement
flagellum power by energy released from mitochondria
26
what is the role of the acrosome and how is it specialised
the acrosome swells and suddenly fuses with the sperm cell surface membrane and releases digestive enzymes which break down the zona pellucida
27
what is the acrosome a type of
a type of lysosome- enzyme filled sacs
28
how is the zona pellucida specialised
sperm fuses and penetrates cell membrane ZP thickens preventing any further sperm
29
what is it called when the zona pellucida hardens
cortical reaction
30
what happens in the acrosome reaction
acrosome swells fuses with cell surface membrane acrosome releases digestive enzymes enzymes break down zona pellucida
31
what happens once the sperm reaches the egg nucleus
a. sperm haploid nucleus fuses with egg haploid nucleus to produce a fertilised egg (zygote)
32
What is the loci (locus)
Location of a gene on a chromosome
33
Why might some genes be more likely to be found together than others
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
Why do some genetic conditions occur in men more often than women
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
What happens before division in meiosis
chromosomes replicate before division
36
What is found before replication in meiosis
Homologous pair of chromosomes
37
what is each chromosome made up of after replication
two chromatids
38
What happens in meiosis 1
Homologous chromosomes pair up separately
39
What happens in meiosis 2
Second division splitting of chromatids
40
What is independent assortment
the chromosomes pairs randomly line up before the first stage of meiosis
41
What is crossing over
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
What is where chromosomes break called
Chiasma
43
what are the 3 stages of mitosis
prophase, metaphase, anaphase and telophase
44
what happens in prophase
chromosomes condense, becoming shorted and thicker spindles form and chromosomes move to equator
45
what happens in metaphase
chromosomes centromeres attach to spindle fibres
46
what happens in anaphase
centromeres split and spindle fibres shorten pulling the two halves in opposite directions towards the poles
47
What happens in telophase?
chromosomes unravel and are enclosed in a separate nuclear envelope
48
what is meant by stem cells
cells from which all other cells are specialised
49
what is meant by pluripotent
can give rise to most cell types but not all cells that makeup the human body
50
what is meant by totipotency
totipotent cells can develop into all types of cells in a complete human
51
how do genes become specialised through gene expression
specialised cells are only expressing some of their genes as only specific proteins are being synthesised
52
what happens in the lac operon model when lactose is absent
RNA polymerase cannot bind a repressor molecule is blocking the operator so B-galactosidase cannot be produced
53
what happens in the lac operon model when lactose is present
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
what is a cell
in multicellular organisms cells are specialised for a particular function
55
what is a tissue
a group of specialised cells working together to carry out a particular function
56
what is an organ
group of tissues working together to carry out one function
57
what is the phenotype a result of
a reaction between genotype and environment
58
what is the epigenome
influences which genes can be transcribed in a particular cell
59
what happens if DNA methylation increases
methyl group attaches to DNA preventing transcription any further
60
what does the acetyl group do
the addition of an acetyl group to the histone tail causes the DNA to wrap less tightly around the histone
61
How can epigenetic changes be passed on after cell division?
the histones are copied along with the DNA
62
what is meant by polygenic inheritance
when a number of genes are involved in the inheritance of a characteristic
63
what is meant by multifactorial inheritance
when conditions of several genetic factors and one or more environmental factors are involved

Biology Edexcel A Alevel (15 decks)

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