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cell structure Flashcards

1
Q

what is magnification

A

how much larger something looks compared to its actual size

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2
Q

what is resolution

A

the ability to distinguish from two points

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3
Q

why should cells be kept cold before homogenisation

A

stop enzymes from reacting and breaking down cell organelles

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4
Q

why should cells be kept in an isotonic solution before homogenisation

A

it contains salts and sugars needed to prevent osmosis in the cells

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5
Q

why should cells be kept in a buffer before homogenisation

A

to prevent enzymes from denaturing due to pH fluctuation

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6
Q

how are cells homogenised

A

mixed in a homogeniser at controlled conditions and then filtered to remove large bits of cell wall / membrane

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7
Q

what is ultracentrifugation

A

cell fragments are placed in a centrifuge and spun at a low speed

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8
Q

what is produced after ultracentrifugation

A

heavier organelles fall to the bottom to from a pellet and the remaining liquid at the top is the supernatant

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9
Q

how to get smaller organelles out of ultracentrifugation

A

repeat the process spinning the supernatant at increasing speeds

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10
Q

why should the homogenate be put evenly each side of the centrifuge

A

because it works with gravity so needs to be balanced

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11
Q

what is the order of cell organelles produced after ultracentrifugation

A

nuclei
- chloroplast
mitochondria
lysosomes
ribosomes

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12
Q

how does a transmission electron microscope work

A

it fires electrons through a thin piece of specimen
the electron beam is focused using an electromagnet and denser parts of the specimen absorbs more electrons so appears darker
an image is produced on photographic paper

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13
Q

why is at TEM better than a light microscope

A

beams of electrons have a shorter wavelength than light
They can magnify an object up to 500,000 times
high resolving power

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14
Q

limitations of a TEM

A

living specimen cannot be used because the whole system is a vacuum
specimen must be very thin
chemically fixing the specimen is time consuming
this can result in artifacts
only 2D images are captured but they ca be built up to make 3D)
expensive

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15
Q

what is an artifact

A

accidentally ruining a sample

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16
Q

how does a scanning electron microscope work

A

electrons are passed across the surface of the specimen
scattered electrons form an image on the screen
depressions appear dark and extensions appear light
3D appearance

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17
Q

good things about SEM

A

3D images
500,000 magnification
less chance of an artifact because prep is less complex
specimen don’t have to be cut so thin

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18
Q

limitations of an SEM

A

resolving power is lower
expensive

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19
Q

what is the structure and function of the cell surface membrane

A

s-phospholipid bi-layer
f-regulates the transport of materials in and out of the cell

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20
Q

what is the structure and function of the nucleus

A

s-it contains a nuclear envelope, nucleolus, and chromosones
f- to hold genetic material for the cell

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21
Q

what is the function of the nucleolus

A

synthesis of ribosomes

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22
Q

what is the structure and function of the nuclear envelope

A

s- porus
f- messenger RNA and ribosomes leave

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23
Q

what is the structure and functions of the chromosomes

A

s - protein bound linear DNA found in a diffuse form
f - copying genetic material accurately during cell division

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24
Q

what is the structure and function of the mitochondria

A

s- cristae is the folded inner membrane , matrix contains proteins, lipids , ribosomes and DNA
f - aerobic respiration and production of ATP

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25
what is the structure and function of chloroplast
s- outer membrane, inner membrane and thylakoid membrane which separates the intermembrane space, thylakoid and stroma f- photosynthesis
26
what is the structure and function of the golgi body
s- a stack of flattened stacks surrounded by membranes f- packages and modifies proteins, processes enzymes, secretes carbohydrates
27
what is the structure and function of lysosomes
s - small vesicles produced by the golgi body f- contains digestive enzymes(lysozymes) which hydrolyses old cell organelles or pathogens fagocytes contain a lot
28
what is the structure and function of ribosomes
s- tiny granuals made from two subunits that exist in two sizes 80s in eukaryotic cells and 70s in prokaryotic cells f - protein synthysis
29
what is the structure and function of the rough endoplasmic reticulum
s- membranes enclosed in a network of tubes all cisternae continuous to the outer layer of the nuclear envelope f- protein synthesis because ribosomes are attached and it is closer to the MRNA
30
what is the structure and function of the cell wall
s- cellulose , fully permeable f- structural support
31
what is the function of the vacuole
f- stores sugar to maintain turgidity of the cell
32
how are proteins and lipids modified
vesicle containing proteins from the RER transfer substance to the golgi body primary lysosomes are formed membrane forms around the worn out cell organelle enzymes hydrolyse the particle soluble products are absorbed into the cytoplasm insoluble debris is egested
33
examples of specialised cells
red blood cells sperm egg nerve cell muscle cell
34
what is the process of specialisation known as
cell differentiation
35
how many chromosomes are in one cell
46 identical chromosomes
36
how does cell differentiation occur
change in gene expression to determine which gene is needed for it to develop into a specialised cell
37
definition of a cell
a membrane bound structure containing nucleic acid , proteins and polysaccharides
38
definition of a tissue
a group of specialised cells working together to perform a similar function
39
definition of an organ
different tissues working together to carry out a similar function
40
what are some blood vessels organs and other are not
capillaries are not organs but veins and arteries are because a capillary is only one tissue whilst veins and arteries have many
41
what is a plasmid and what does it do
a small section of DNA which codes for special characteristics
42
what does the cytoplasm do in a prokaryotic cell
metabolic reactions
43
what does the slime capsule do in a prokaryotic cell
prevents them from drying out and makes them to slippery to be engulfed by white blood cells
44
what does the cell wall do in a prokaryotic cell and what is it made of
maintains cell shape made of murain which is a glycoprotein
45
what does the flagellum do in a prokaryotic cell
rotates to propel the cell
46
what does the free flowing DNA in a prokaryotic cell do
codes for normal functions
47
what is the matrix in a virus cell
a layer of proteins situated under the outer envelope
48
what are attachment proteins in a virus cell
proteins used to identify and attach to the host cell
49
what is a capsid in a virus cell
protein layer that encapsulates two single strands of RNA and some enzymes
50
what does the genetic material in a virus cell do
needed for reproduction
51
what is the lipid envelope in a virus cell
allows enveloped viruses to bud out the cell without damaging the cell membrane (not all viruses have them)
52
what is a reverse transcriptase in a virus cell
an enzyme that catalyses the production of DNA from RNA
53
what type of reproduction is mitosis and where does it occur
a sexual in sematic cells
54
what is produced after mitosis
two new identical daughter cells with the same number of chromosomes as the parent cell
55
why is mitosis important
growth of tissues or organisms replacing damaged or old cells
56
what is the equation for the MI value
number of cells with condensed chromosomes/total number of cells x 100
57
what happens to the chromosomes in prophase
long threads get shorter and thicker the centriole is in the poles produce spindle fibres (if its an animal cell) the nuclear envelope breaks down and chromatids are free in cytoplasm
58
what happens to the chromosomes in metaphase
chromatids are joined together at the centromere the spindle fibres pull chromatids to the equator and bind with the centromere
59
what happens to the chromosomes in anaphase
the centromere divides in two and the spindle fibres pull the chromatids to the opposing poles
60
what happens to the chromosomes in telophase
chromosomes at the poles become longer and thinner until they disappear leaving a wide spread chromatin. nuclear envelope reforms and cytokinesis occurs
61
how do prokaryotic cells divide
by binary fission
62
what happens in G1
cell growth before DNA replication
63
what happens in S
chromosomes are duplicated
64
what happens in G2
after DNA replication and cells prepare to divide
65
what are G1 S G2 all called
interphase
66
what causes cancer
damage to genes by mutation or environment causing quick and uncontrollable cell division
67
what is a benign tumor
a tumor that doesn't spread to other tissue
68
what is a malignant tumor
a tumor that infiltrates other tissue
69
how do cancer cells move around the body
through blood and lymth fluid
70
what does metastases mean
spread (secondary cancer )
71
what happens in binary fission
replication of DNA and plasmids division of cytoplasm to produce two daughter cells each with a single copy of DNA and variable plasmids
72

biology (29 decks)

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