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Biology > Topic 2.2 - Cell Structure and Divison > Flashcards

Topic 2.2 - Cell Structure and Divison Flashcards

1
Q

Describe the function and structure of a cell surface membrane in eukaryotic cells

A

Description:
- Made of phospholipid bilayer (lipids and proteins)
Function:
- Controls the movement of substances in and out of cells
- Receptor molecules (respond to chemicals e.g. hormones

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2
Q

Describe the function and structure of a nucleus in eukaryotic cells

A

Description:
- Double membrane (nuclear envelope)
- Pores (holes) which allows substances to move between the nucleus and the cytoplasm
Function:
- Controls all activities in the cell
- Stores genetic material as chromatin
- Nucleolus which makes ribosomes and RNA

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3
Q

Describe the function and structure of a mitochondria in eukaryotic cells

A

Description:
- Double membrane
- Folded inner membrane (cristae)
- Matrix contains enzymes involved in respiration (found in the inner membrane)
Function:
- Where ATP (energy) is released from aerobic respiration

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4
Q

Describe the function and structure of a chloroplast in eukaryotic cells

A

Description:
- Double membrane
- Chlorophyll found in stacks (grana) of thylakoid membranes
- Grana linked together by lamellae
- Contains stroma (thick fluid)
Function:
- Absorbs light for photosynthesis

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5
Q

Describe the function and structure of a
Golgi apparatus in eukaryotic cells

A

Description:
- Fluid filled flattened sacs
Function:
- Processes and packages new lipids and proteins
- Modifies them by adding sugar
- Makes lysosomes

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6
Q

Describe the function and structure of a Golgi vesicle in eukaryotic cells

A

Description:
- Produced by the Golgi apparatus
- Small fluid filled sacs
Function:
- Stores lipids and proteins made by the Golgi apparatus
- Transports lipids and proteins out (via the cells surface membrane)

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7
Q

Describe the function and structure of a lysosome in eukaryotic cells

A

Description:
- Contains lysozymes (digestive enzymes)
Function:
- Digest invading pathogens and worn out components of the cell

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8
Q

Describe the function and structure of a ribosome in eukaryotic cells

A

Description:
- Not membrane bound
- Made up of proteins and RNA
- Bound to RER or free in cytoplasm
Function:
- Site of protein synthesis

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9
Q

Describe the function and structure of a rough endoplasmic reticulum (RER) in eukaryotic cells

A

Description:
- Surface covered with ribosomes
- Series of flattened membrane bound sacs called cisternae
Function:
- Transports proteins made on ribosomes

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10
Q

Describe the function and structure of a smooth endoplasmic reticulum (SER) in eukaryotic cells

A

Description:
- Surface not covered with ribosomes
Function:
- Makes and processes lipids

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11
Q

Describe the function and structure of a cell wall in eukaryotic cells

A

Description:
- Plants = Made of carbohydrate cellulose
- Fungi = Made of chitin
- Plasmodesma (channels for exchanging substances)
Function:
- Gives structure and shape to the cell

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12
Q

Describe the function and structure of a cell vacuole in eukaryotic cells

A

Description:
- Tonoplast (surrounding membrane)
- Contains cell sap (a weak solution of sugar and salts)
Function:
- Helps to maintain pressure inside the cell

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13
Q

Do prokaryotic cells have membrane bound organelles?

A

No

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14
Q

Describe the function and structure of a cell wall in prokaryotic cells

A

Description:
- Contains muerin
Structure:
- Supports and helps keep shape to the cell

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15
Q

Describe the function and structure of a mesosome in prokaryotic cells

A

Description:
- Extension of plasma membrane
Function:
- Functions in either DNA replication and cell division or excretion of enzymes

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16
Q

Describe the structure of a ribosome in prokaryotic cells

A

Smaller than ribosomes in eukaryotic cells

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17
Q

Describe the function of food granules in prokaryotic cells

A

Food reserves
Often made of glycogen or other carbohydrates

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18
Q

Describe the function of a flagella in prokaryotic cells

A

For motility

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19
Q

Describe the structure of a plasmid in prokaryotic cells

A

Small loops of DNA

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20
Q

Describe the function and structure of a capsule in prokaryotic cells

A

Description:
- Secreted slime layer
Function:
- Protect against attacking immune cells

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21
Q

Describe the function of pili in prokaryotic cells

A

Attachment to other cells

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22
Q

Describe the function and structure of a custom in prokaryotic cells

A

A semi-fluid filled substance embedding other organelles

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23
Q

Where is DNA found in prokaryotic cells?

A

DNA floats freely in the cytoplasm as one coiled up strand because prokaryotic cells don’t have a nucleus

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24
Q

What is binary fission?

A

The process by which prokaryotic cells replicate

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26
What is a virus?
An acellular structure that invades and reproduces inside the cells of other organisms (causing disease)
27
Describe the structure of viruses
- Core = contains genetic material - Capsid = protein coat which surrounds the viral genome - Attachment proteins = allows viruses to attach to host cells
28
What are three examples of viruses?
- HIV - Influenza - Rhinoviruses
29
Describe the process of binary fission of a virus
1) Viruses attach to host cell by binding their attachment proteins to their complementary cell surface receptor proteins 2) They inject their DNA or RNA into the host cell or enter by exocytosis 3) Genetic material and proteins are replicated using the cell’s machinery (enzymes and proteins) 4) Viral components assemble to form new viral particles 5) Replicated virus particles released from the host cell (budding)
30
Why can viruses only infect one type of cell?
Different viruses have different attachment proteins and require different complementary receptor proteins in host cells
31
What is a specialised cell?
A cell adapted to carry out specific functions
32
What are the function of adaptations of sperm cells?
Function: - Fertilises egg Adaptations: - Long tail = swim quickly - Mitochondria = lots of energy to swim quickly - Acrosome = contains
33
What are the function of adaptations of xylem cells?
Function: - Transports water and mineral ions up a plant Adaptations: - Lignin = prevents collapse as water passes through - Pits = allows water movement sideways
34
What are the function of adaptations of ciliated epithelial cells?
Function: - Move fluids and particles along surface of tissue Adaptations: - Cilia = rapid, rhythmical beating to move substances - Column shape = lining of organs - Associated goblet cells = secretion of mucus
35
What are the function of adaptations of phloem vessels?
Function: - Transports organic substances (e.g. sugars) around the plant Adaptations: - Sieve tubes = bidirectional flow = allows solutes to travel throughout the plant - Sieve plates = allows flow of solutes - Companion cells = carry out living functions of sieve plates - Mitochondria = active transport of solutes
36
What are the function of adaptations of guard cells?
Function: - Controls opening and closing of stomata Adaptations: - Large vacuole = becomes turgid to open stomata = becomes flacid to close stomata - Thick inner cell wall = uneven - Two surrounding stoma = allows control of gas exchange - Sunken stoma = reduces transpiration
37
What are the function of adaptations of neutrophils?
Function: - First responders in immune response Adaptations: - Many lysosomes = digestive enzymes (lysozymes) used during phagocytosis
38
What are the function of adaptations of erythrocytes (red blood cells)?
Function: - Carries oxygen around the body Adaptations: - Biconcave shape = large surface area for diffusion of oxygen - Haemoglobin = proteins bind with oxygen to form oxyhemoglobin - No nucleus = more space for haemoglobin
39
Define magnification
how many times bigger the image is compared to the actual specimen
40
Define resolution
How well a microscope can distinguish between two points
41
What is the formula to calculate magnification?
Magnification = Image size / Actual size
42
How do you prepare slides before viewing them under an optical microscope?
1) Pipettes a small drop of water on the centre of the slide 2) Place thin section of specimen on the water drop in n the temporary mount 3) Add a drop of stain 4) Add cover slip carefully. Avoid air bubbles
43
Why are thin specimens viewed under a microscope?
So light can pass through
44
What is a stain added to slide before viewing it under a microscope?
Highlights objects in a cell
45
What are the three types of microscopes?
- Optical (light) microscope - Transmission electron microscope (TEM) - Scanning electron microscopes (SEM)
46
How does an optical (light) microscope work?
Light focuses through a lens to form a magnified image
47
How does a transmission electron microscope work?
- Electrons transmitted across thick specimen - View specimen in vacuum Image viewed: 3D Surface of specimen viewed Monochrome Lower resolution
48
How do scanning electron microscopes work?
- Electrons transmitted across thick specimen - View specimen in vacuum Image viewed: 3D Surface of specimen viewed Monochrome Lower resolution
49
How are slides prepared before viewing them under a transmission electron microscope ?
- Complex preparation - Specimen placed in fixing solution, dehydrated and embedded in resin - Sections cut using ultramicrotome into very thin sections
50
How are slides prepared before viewing them under a scanning electron microscope?
- Complex preparations - Drying of specimen - Coating specimen with conducting material
51
Define artefacts
- Things seen that are not part of the specimen - Usually due to incorrect preparation of specimen - E.g. air bubbles finger prints
52
What is a stage micrometer used for?
Used to work out the value of divisions on the eyepiece graticule of a particular magnification
53
What is an eyepiece graticule used for?
- A scale in the eyepiece lens which which represents different lengths at different t magnifications - Scale has to be re-calibrated each time using scale micrometer (overlaps)
54
Define cell fractionation
The process that separates the organelles in a cell
55
What is the process of cell fractionation
1) Homogenisation - Cells are broken up in a homogeniser - Plasma membrane is broken, releasing organelles from the cell into solution (homogenate) Solutions must be ice cold, isotonic and buffer 2) Filtration - Homogenate is filtered through a gauze to separate large cell debris and any whole cells from the organelles - Organelles (small) pass through gauze 3) Ultracentrifugation - Cells fragments are poured in tube - Tube put into centrifuge (blender) - Used to separate particular organelles from solution of mixed organelles by their different densities - Centrifuge spun at low speed to separate out heaviest organelles (nuclei) - Form pellet (thick sediment) at bottom of the tube - Rest of organelles stay suspended in the fluid above pellet (supernatant) - Supernatant is put into a different tube and centrifuged at a higher speed to separate out the next heaviest organelles - Repeated at higher and higher speeds until all organelles are separated out
56
Why must the homogenate be ice cold?
To reduce enzyme activity that break down organelles
57
Why must the homogenate be isotonic?
- Same concentration of chemicals as cells being broken down - Prevent damage to organelles by osmosis
58
Why must the homogenate be a buffer?
Maintains pH to prevent enzymes denaturing
59
Define cell debris
Organic waste that is left (usually after a cell cycle)
60
Define interphase
A period of the cell cycle in which the cell grows and DNA is replicated
61
Define mitosis
A type of cell division where a parent cell divides to produce two genetically identical daughter cells Used for: - growth - repairing damaged tissue
62
What are four examples of cells that do not undergo the cell cycle? Give reasons for each
- Red blood cells > no nucleus > made in bone marrow - White blood cells > made in bone marrow - Muscle cells > myobkasts fuse - Nerve cells > neurones are made in the brain
63
Describe the cell cycle
1) G1 phase - New organelles and proteins in cells are made and grow - Cell components needed by new cell are duplicated 2) S phase - DNA unravelled and replicated - Each chromosome duplicates and becomes two strands (each called a chromatid) - ATP content increases - Two chromatids are joined at the centromere 3) G2 phase - Cell keeps growing - Enzymes check for mutations 4) Mitosis - Cell division (resulting in two identical daughter cells) 5) Cytokinesis - Cytoplasm divides (two new cells are formed) - Each cell contains a full set of chromosomes, genetically identical to original parent cell
64
Define centrioles
Tiny bundles of protein that produce spindle fibres
65
What does the length of each stage of mitosis depend on?
- Cell type - Environmental conditions
66
Describe the process of mitosis
1) Prophase - Chromosomes condense, shorten and thicken (supercoil) - Centrioles move to opposite poles of the cell - Spindle fibres created - Nuclear envelope breaks down - Chromosomes lies free in the cytoplasm 2) Metaphase - Chromosomes (each with two chromatids) line up along the equator - Spindle fibres attach to the centromere of sister chromatids 3) Anaphase - Spindle fibres contract and pull on centromeres, making them divide - Sister chromatids move to opposite poles of the cell 4) Telophase - Chromosomes uncoil (long and thin) - Chromosomes are no longer visible - 2 nuclear envelopes form around each set of chromosomes (2 nuclei)
67
Describe the process of cytokinesis
- Cytoplasm divides - Two genetically identical daughter cells produced (genetically identical to original parent cell)
68
Define mitotic index
Proportion of cells in a sample undergoing mitosis
69
How do you calculate Mitotic index ?
Mitotic index = (number of cells undergoing mitosis / total number of cells) x 100
70
Define pluripotent cells
A cell that has the ability to change into any type of cell
71
Define cancer
A condition where cells grow and reproduce uncontrollably
72
What are the two types of tumours? Describe them
- Benign = cells grow and reproduce but do not spread - Malignant = cells can invade and destroy surrounding healthy tissues, including organs, by moving to different sites
73
Define metastasis
- A mutated tumour cell that breaks off and is transported via the bloodstream to other organs and tissues - The cell invades the tissue and develops into a secondary tissue
74
What are some risk factors of cancer? Give 5 examples
- Radiation exposure - Alcohol / tobacco use - Diet > high in fat > low in fruit / vegetables - Genetics - Viruses
75
Define proto-oncogenes
A group of genes in a cell that regulate cell division (mitosis) by producing proteins
76
Why do cancer treatments also kill healthy cells?
Treatments cannot distinguish between cancerous cells and healthy cells
77
Define apoptosis
Process of programmed cell death
79
Describe the process of binary fission
1) Single, circular DNA and plasmids replicate 2) Cells grow larger Single, circular DNA loops move to opposite poles of the cell 3) Cytoplasm begins to divide New cell walls form 4) Cytoplasm divides 2 daughter cells are produced

Biology (4 decks)

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