Cell structure Flashcards
1
Q
What is the difference btw animal cells and plant cells?
A
- Plant cells have:
- Cellulose cell wall
- Vacuole
- Chloroplast
2
Q
Describe the structure of an algal cell
A
Same organelles as plant cell
3
Q
What are the differences btw fungal cells + plant cells?
A
- Cell walls are made of chitin
- Don’t have chloroplast
4
Q
Cell surface membrane
A
- Made of lipids + protein
- Regulates movement of substances in + out of cell
- Has receptor molecules so it responds to chemicals
5
Q
Nucleus
A
- Organelle surrounded by nuclear envelope w/ pores. Contains c’somes called nucleolus
- Controls cell’s activities
- DNA contains instructions to make proteins
- Pores allow substances to move btw nucleus + cytoplasm
- Nucleolus makes ribosomes
6
Q
Mitochondria
A
- Double membrane, inner folding called cristae. Inside is matrix which contains enzymes involved in respiration
- Site of aerobic respiration, where ATP is produced
7
Q
Chloroplast
A
- Found in plants + algae. Has double membrane + thylakoid that stack up to form granum linked together by lamellae surrounded by stroma
- Site where photosynthesis takes place
8
Q
Golgi apparatus
A
- Fluid filled, membrane bound flattened sacs. Has vesicles
- Processes + packages lipids + proteins
- Also makes lysosomes
9
Q
Golgi vesicles
A
- Small fluid filled sac
- Stores lipids + proteins made by golgi apparatus + transports them out of cell
10
Q
Lysosomes
A
- Round organelle, type of golgi vesicle
- Contains digestive enzymes - lysozymes, digest invading cells or break down worn out components of cell
11
Q
Rough endoplasmic reticulum
A
- Covered in ribosomes
- Folds + processes proteins made at ribosomes
12
Q
Smooth endoplasmic reticulum
A
- No ribosomes
- Synthesises + processes lipids
13
Q
Cell wall
A
- Made of cellulose/chitin
- Supports cell + prevents shape change
14
Q
Cell vacuole
A
- Contains cell sap + membrane made from tonoplast
- Helps maintain pressure inside cell + keep it rigid - stops wilting
- Involved in isolation of unwanted chemicals inside cell
15
Q
Compare a eukaryotic cell to a prokaryotic cell
A
- Smaller + simpler than eukaryotic
- Doesn’t have a nucleus
- DNA is circular
16
Q
What are the differences btw prokaryotic cells + viruses?
A
- Smaller
- No plasma membrane
- No cytoplasm
- No ribosomes
17
Q
Outline how prokaryotic cells replicate
A
- Binary fission
- Circular DNA + plasmid replicate - DNA once, plasmid loads
- Cell gets bigger + DNA loop moves to opposite poles of cell
- Cytoplasm divides + new cell wall form
- 2 daughter cells produced - 1 copy of circular DNA but variable no. plasmid
18
Q
Outline how viruses replicate
A
- Use attachment protein to bind to complimentary receptor protein on surface of host cell
- Inject DNA/RNA into host cell
- Uses cells machinery to replicate
19
Q
Define resolution
A
How well a microscope distinguishes btw 2 points that are close together
20
Q
Describe a light microscope
A
- Uses light
- Can’t use to view smaller organelles
- Max magnification is x1500
21
Q
Describe an electron microscope
A
- Use e-
- Higher resolution so give more detailed image
- Max magnification is x1500000
22
Q
Describe a transmission electron microscope
A
- Uses electromagnets to focus beam of e-, which is transmitted through specimen
- Denser parts absorb more e- so look darker
- High resolution so can see internal organelles
- Needs thin specimen
23
Q
Describe a scanning electron microscope
A
- Scan beam of e- across specimen, knocks off e- from specimen which are gathered in cathode ray tube to form image
- 3D image
- Can use thick specimen
- Lower resolution than TEMs
24
Q
How do you prepare for a temporary mount?
A
- Pipette small drop of water onto slide
- Place thin section of specimen on top of water using tweezers
- Add stain to highlight objects
- Add cover slip using mounting needle
25
Q
Outline how to carry out cell fractionation
A
- Homogenisation - grind cells in blender to break plasma membrane + release organelles into sol (ice cold, isotonic + buffer)
- Filteration - filter through gauze to seperate debris from organelle
- Ultracentrifugation - spun at low speed in centrifuge, heaviest form pellet at bottom, the rest is supernatent + drained off in another tube
26
Q
What is mitosis needed for?
A
- Growth
- Repairing damaged tissue
27
Q
What happens before mitosis?
A
- Interphase
- DNA unravels + replicates
- Organelles replicate
- ATP inc
28
Q
What happens at prophase?
A
- Csomes condense + get shorter + fatter
- Centrioles move to opposite ends of cell forming spindles
- Nuclear envelope breaks down + csomes lie free in cytoplasm
29
Q
What happens at metaphase?
A
- Csome line up along middle of cell
- Attach to spindle fibre at centromere
30
Q
What happens at anaphase?
A
- Centromeres divide seperating each pair of sister chromatids
- Spindle contracts pulling chromatids to opposite poles of spindle
31
Q
What happens at telophase?
A
- Chromatids reach opposite poles
- Uncoil + become long + thin - csomes again
- Nuclear envelope form round each group of csome - 2 nuclei
- Cytoplasm divides
32
Q
What causes cancer?
A
- Mutation in gene that controls cell division, uncontrollable cell growth forms tumour
- Cancer = tumour that invades surrounding tissue
33
Q
Give examples of cancer treatment
A
- Some drugs prevent synthesis of enzymes needed for DNA replication, if not produced, unable to enter synthesis stage forcing cell to kill itself
- Radiation damage DNA, DNA checked for damage, if damaged cell will kill itself
34
Q
Outline how you would carry out an experiment to observe mitosis
A
- Cut tip from growing root - where mitosis occurs
- Prepare boiling tube w/ HCL + put in water bath
- Transfer root tip into boiling tube
- Use pipette to rinse root tip w/ cold water, dry tip
- Put on microscope slide + use mounting needle to break tip open
- Add stain + place cover slip
35
Q
How do you set up an eyepiece graticule?
A
- Line eyepiece graticule + stage micrometer
