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Biology > 2.1.6 > Flashcards

2.1.6 Flashcards

1
Q

what happens in phase 1 of interphase G1

A

proteins from which organelles are synthesised are produced and organelles replicate
Cell increases in size

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2
Q

What happens in S phase of interphase

A

DNA is replicated in nucleus

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3
Q

In G2 cells

A

continue to increase in size
energy stores increased
duplicated DNA checked for errors

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4
Q

mitotic phase consists of

A

mitosis
cytokinesis

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5
Q

In cytokineses

A

cytoplasm divides and two celles produced

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6
Q

three reasons a cell leaves cell cycle and enters G0

A

Differentiation (specialised cell carries out its function)
Damaged DNA(damaged cell cant divide)
Age(more senescent cells)

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7
Q

checkpoints monitor and

A

verify whether processes at each phase of cell cycle have been accurately completed before cell can progress into next phase

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8
Q

want is checked at the different checkpoints

A

G1
cell size, nutrients, growth factors, DNA damage
G2
cell size DNA damage and replication

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9
Q

the metaphase checkpoint is at the point

A

where all chromosomes are attached to spindles and aligned

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10
Q

how can we treat cancer(rapid division)

A

prevent DNA replication
Inhibit metaphase

but this would affect normal cells(hair loss)

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11
Q

how can we treat cancer(rapid division)

A

prevent DNA replication
Inhibit metaphase

but this would affect normal cells(hair loss)

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12
Q

mitosis refers to

A

nuclear division

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13
Q

When replicated Each chromosome converted into two identical chromosomes called

A

chromatids

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14
Q

two chromatids held together at

A

centromere

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15
Q

in prophase

A

chromatin fibres coil and condense into chromosomes
nucleolus disappears
nuclear membrane breaks down

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16
Q

prophase
spindle fibres link poles of cell
two centrioles migrate to

A

opposite ends of cell
spindle fibres attach to centromeres and start to move chromosomes to centre of cell
By end nuclear envelope disappeared

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17
Q

Metaphase
chromosomes are

A

moved by the spindle fibres to form metaphase plate and held here

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18
Q

In anaphase

A

centromeres divide
chromatids separated and pulled opposite ends cell by shortening spindle fibres

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19
Q

In telophase

A

chromatids at poles now chromosomes
nuclear envelope reforms
chromosomes uncoil
nucleolus forms
mitosis over cytokinesis then begins

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20
Q

Cytokinesis in animal cells

A

cleavage furrow middle of cell
cell surface membrane pulled inwards until can fuse

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21
Q

cytokinesis in plant cells

A

vesicles assemble middle of cell
fuse with eachother and cell surface membrane
cell wall then forms along membrane

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22
Q

Gamete is a haploid

A

cell involved in sexual reproduction

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23
Q

homologous chromosomes are

A

pairs of genes for each characteristic

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24
Q

each chromosome in a homologous pair has the same gene at the same

A

loci

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25
Different alleles of a gene have the same locus()
(position on a particular chromosome)
26
why are homologous chromosomes same size
same genes in same positions
27
Meiosis 1 overview
réduction division pair of homologous chromosomes separated after first division cells are haploid
28
Meiosis 2 overview
pairs of chromatids are separated four haploid daughter produced
29
Meiosis 1 Prophase 1 homologous chromosomes
pair up forming bivalents
30
chromatids entangling is called
crossing over
31
Meiosis 1 Metaphase 1
homologous pairs of chromosomes assemble along metaphase plate
32
what is independent assortment and what does it result in
when orientation of each homologous pair on metaphase plate is random and independent of any other pair maternal could face either pole results in genetic variation
33
Anaphase 1
chromatids stay joined to eachother but homologous pairs pulled to each pole
34
genetic variation in random fertilisation
any sperm can fertilise any egg each individual won’t exist before or again
35
genetic recombination takes place at random
chromosomes can cross over and swap blocks of genes
36
chiasma is the point
where chromosomes cross over
37
reduction division is where
less chromosomes after division
38
telophase 1 summary
chromosomes assemble at pole nuclear membrane forms chromosomes uncoil
39
meiosis cells after first division are
haploid
40
in prophase 2 chromosomes condense and
nuclear envelope breaks down spindle formations starts
41
in Metaphase 2 what assembles on the metaphase plate
individual chromosomes
42
because of crossing over
chromatids aren’t identical so there is independent assortment and genetic variation
43
anaphase 2 the chromatids of the individual chromosomes
are pulled to poles after division of centromeres
44
what happens telophase 2
chromatids assemble at poles and uncoil form chromatin envelope reforms nucleolus visible
45
cells after meiosis are haploid due to
reduction division
46
why are daughter cells genetically different in meiosis
crossing over and independent assortment
47
point of breakage of cross over is
chiasmata
48
what shape does a erythrocyte have
biconcave to increase sa:v
49
Give two properties of erythrocytes and how this relates to function
No nuclei mitochondria golgi apparatus RER makes more space for the protein haemoglobin flexible squeeze through narrow capillaries
50
shape of a neutrophil nucleus
multi lobed nucleus for fitting in small gaps
51
granular cytoplasm in neutrophil contains
lysosomes which contain digestive enzymes
52
shape of squamous epithelial cell
flat and thin for rapid diffusion one cell thick
53
one example of use of squamous epithelial cells
lines lungs rapid diffusion oxygen into blood
54
why are palisade cells tall and thin
so can be closely packed in a continuous layer for light absorption thin cell walls increase rate of diffusion for carbon dioxide
55
in palisade cells chloroplasts can move
within cytoplasm
56
why do palisade cells have a large vacuole
maintains turgor pressure
57
in a guard cell when stoma is open it is
turgid and co2 enters
58
a tissue is made up of
a collection of differentiated cells that have a specialised function(s) thus each tissue adapted to particular role within organism
59
cartilage is a connective tissue chondrocyte cells produce
extracellular matrix of collagen fibres(strength) and elastin fibres (flexibility)
60
skeletal muscle fibres contain myofibrils which contain
contractile proteins
61
three types of muscle tissue
skeletal-movement smooth-involuntary cardiac-heart
62
a bundle of muscle fibres is called a
fascicle
63
two tissues in plants
epidermis vascular
64
vascular tissue in plants is for
transport
65
in xylem tissue
elongated dead cells walls strengthened by lignin no cytoplasm wide lumen
66
parenchyma cells do what with xylem tissue
fill gaps
67
phloem tissue is responsible for the transport
of organic nutrients
68
an organ is a
collection of tissues that are adapted to perform a particular function in an organism
69
what is an organ system
number of organs working together for the same function in body digestive system takes on food breaks down large insoluble molecules into smaller soluble ones absorbs nutrients retains water removes undigested material from body
70
stem cells are
undifferentiated unspecialised cells that can become any one of the range of specialised cells in the organism
71
once stem cells have become specialised they lose the
ability to divide entering G0 phase of cell cycle
72
why does stem cell activity have to be strictly controlled
if don’t divide fast enough tissues aren’t efficiently replaced (aging) divide too fast tumours and cancer
73
the greater the number of cell types a stem cell can differentiate into
the greater it’s potency
74
totipotent stem cells can
differentiate into any and all types of cells zygote and cells from its first few divisions
75
pluripotent stem cells can form all tissue types but not
whole organisms
76
pluripotent stem cells can form all tissue types but not
whole organisms
77
multi potent stem cells can only
form a range of cells within a certain type of tissue
78
all blood cells are derived from stem cells in
the bone marrow
79
due to lack of nucleus and organelles erythrocytes
have lifespan of 120 days constantly need to be replaced
80
neutrophils live for
6 hours!
81
embryonic stem cells are
totipotent
82
after seven days what have embryonic stem cells formed
mass of cells blastocyst pluripotent
83
tissue(adult) stem cells are
found in specific areas multi potent
84
where are stem cells found in plants
meristematic tissue which is found wherever growth is occurring tips of roots and shoots( apical meristems)
85
what is vascular cambium
meristematic tissue between phloem and xylem tissue cells originating from this region differentiate into cells present in xylem and phloem tissue
86
give an example of how stem cells have been used
treating burns(grown on biodegradable mesh produce new skin faster than taking a graft from another part their body)
87
why arent alternatives to embryonic stem cells for curing diseases as good
umbilical cord are only multi potent tissue adult stem cells don’t divide as well more likely to have mutations
88
induced pluripotent stem cells are
adult stem cells genetically modified to act like embrionic(pluripotent)

Biology (7 decks)

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