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A level Biology > Cells- Topic 2 > Flashcards

Cells- Topic 2 Flashcards

(67 cards)

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1
Q

Magnification

A

how much the microscope can
increase the image size.

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2
Q

Resolution

A

how well you can determine the
difference between two points.

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3
Q

1m =

A

1,000mm = 1,000,000µm =
1,000,000,000nm. (x 1000)

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4
Q

Magnification =

A

size of image/ size of real object

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5
Q

Light microscope resolution

A

Low resolution due to comparatively large wavelength of light

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6
Q

Light microscope limitations

A

Samples are generally dead, Very thin sample slices are needed, The sample may have to be stained to show up important features eg, nucleus
of cell, The image is 2D

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7
Q

Transmission electron microscope

A

Highest resolution, 2D image, electron beam passes through a thin sample

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8
Q

Transmission Electron microscope limitations

A

Sample must be dead, complex staining process, thin sample, vacuum needed, complex staining process.

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9
Q

Scanning electron microscope

A

3D image, electrons bounce off sample

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10
Q

Scanning electron microscope limitations

A

lower resolution and magnification than TEM, vacuum needed, complex staining process.

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11
Q

Cell fractionation

A

the process by which cells are broken up and the different organelles they contain are separated out

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12
Q

Before homogenisation the sample is placed in a solution which is:

A

Cold, Isotonic and Buffered

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13
Q

Homogenisation

A

Blending the sample to release the cells contents

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14
Q

Filtration

A

Removes impurities from the sample

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15
Q

Ultracentrifugation

A

Spun to form sediment pellets of heaviest component and supernatant which can be respun

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16
Q

Nuclear envelope

A

a double membrane surrounding the nucleus with nuclear pores to control the exit of substances

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17
Q

nucleoplasm

A

semifluid matrix which contains chromatin (less condensed form of DNA)

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18
Q

Nucleolus

A

Centre of the nucleus, produces ribosomes

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19
Q

Nucleus function

A

Controls functions of the cell

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20
Q

Mitochondria function

A

Site of aerobic respiration, produces ATP

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21
Q

Mitochondria double membrane

A

Inner and outer membranes, Controls entry and exit of material

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22
Q

Mitochondria Cristae

A

Extensions of inner membrane (folds), Provide large surface area (attachments of
enzymes and proteins)

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23
Q

Matrix (Mitochondria)

A

Space between cristae, Contains protein, lipids, ribosomes, DNA, enzymes.

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24
Q

Chloroplasts function

A

Site of Photosynthesis

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25
Chloroplast envelope
double plasma membrane: outer and inner membrane, selective, choose what can enter and leave
26
Thylakoids (chloroplasts)
Membranous sacs which contain photosynthetic pigment called chlorophyll (capture light), ATP is made here,
27
Grana (chloroplasts)
stacks of up to 100 disk like thylakoids,
28
lamellae (chloroplasts)
connecting tubes between thylakoids
29
Stroma (chloroplasts)
fluid-filled matrix where sugars are made from carbon dioxide
30
Rough Endoplasmic Reticulum structure
A system of membranes enclosing a fluid-filled space studded with numerous ribosomes
31
Rough Endoplasmic Reticulum function
pathway for transport of materials (proteins) folds and processes proteins that have been made at the ribosomes
32
Smooth Endoplasmic reticulum structure
A system of membranes enclosing a fluid-filled space, no ribosomes
33
Smooth Endoplasmic reticulum function
synthesise, processes, store and transport lipids and carbohydrates
34
Golgi apparatus structure
A group of fluid-filled, membrane-bound flattened sacs. Vesicles are often seen at the edges of the sacs
35
Golgi apparatus function
processes and packages new lipids and proteins, forms glycoproteins. It also makes lysosomes
36
Golgi Vesicle structure
small fluid-filled sac in the cytoplasm, surrounded by a membrane and produced by the Golgi apparatus
37
Golgi Vesicle function
Stores lipids and proteins made by the Golgi apparatus and transports them out of the cell (via the cell-surface membrane)
38
Lysosome structure
Formed when vesicles from Golgi body contain enzymes (protease and lipase and lysozyme)
39
Lysosome function
Hydrolyse material ingested by phagocytic cells (white blood cell, bacteria), Release enzymes to the outside of cell (exocytosis) to destroy material around the cell, Digest worn out organelles, Autolysis – completely break down cells after they have died
40
Ribosomes structure
Made of proteins and rRNA, Two subunits – large and small. 80s in eukaryotes, 70s in prokaryotes
41
Ribosome function
Site of protein synthesis
42
Cell wall structure and function
Microfibrils of polysaccharide embedded in a matrix, provides mechanical strength
43
Cell membrane function
selectively permeable barrier
44
Vacuole structure and function
membrane-bound organelle found in the cytoplasm of plant cells containing cell sap. surrounding membrane is called a tonoplast. Helps to maintain pressure inside the cell and keep the cell rigid, isolates unwanted chemicals.
45
substance in bacterial cell wall
murein
46
DNA store in prokaryotes
circular strand of DNA and plasmids
47
How do bacteria divide
binary fission
48
flagella
tail that some bacteria have
49
Capsule
Outer layer of bacterial cells
50
viruses
acellular, non living particles
51
virus structure
Contain nucleic acids, DNA and RNA, enclosed within a protein coat called the capsid
52
G1 of cell cycle
cell contents duplicated
53
S of cell cycle
DNA duplicates
54
G2 of cell cycle
checking DNA replication and preparing to divide
55
centromere
where 2 sister chromatids are joined
56
interphase
chromosomes duplicate so there is double the amount of genetic information
57
Prophase
prepare. DNA super coils and chromosomes become visible. Nuclear membrane breaks down. Centrioles divide (to form 4) and spindle is assembled
58
centriole
organises the spindle fibres
59
Metaphase
middle. Chromosomes line on equator of cell Spindles fibres attach to centromeres
60
anaphase
apart. Centromere splits Chromatids are pulled to opposite poles as spindle fibres contract
61
telaphase
two. Nuclear membranes reform Chromosomes uncoil Cytokinesis begins
62
Cytokinesis
cell divides to form 2 daughter cells
63
what causes tumours and cancer
uncontrolled cell division
64
how do viruses replicate
by injecting their nucleic acid into host cells
65
mitotic index
the proportion of cells (in a group of cells or a sample of tissue) that are undergoing mitosis. The more rapidly the cells are dividing, the higher the index
66
mitotic index calculation
number of cells in mitosis/ total number of cells
67

A level Biology (8 decks)

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