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
Outline how to carry out cell fractionation
* **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
What is mitosis needed for?
* **Growth**
* **Repairing damaged tissue**
27
What happens before mitosis?
* **Interphase**
* **DNA unravels** + **replicates**
* **Organelles replicate**
* **ATP inc**
28
What happens at prophase?
* **Csomes condense** + get **shorter** + **fatter**
* **Centrioles move** to **opposite ends** of cell forming **spindles**
* **Nuclear envelope breaks down** + csomes lie free in cytoplasm
29
What happens at metaphase?
* **Csome line up** along **middle** of cell
* **Attach** to **spindle fibre** at **centromere**
30
What happens at anaphase?
* **Centromeres divide seperating** each pair of **sister chromatids**
* **Spindle contracts** pulling **chromatids** to **opposite poles** of spindle
31
What happens at telophase?
* **Chromatids reach opposite poles**
* **Uncoil** + become **long** + **thin** - csomes again
* **Nuclear envelope form** round each group of csome - 2 nuclei
* **Cytoplasm divides**
32
What causes cancer?
* **Mutation** in **gene** that **controls cell division**, **uncontrollable cell growth** forms tumour
* Cancer = **tumour** that **invades surrounding tissue**
33
Give examples of cancer treatment
* 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
Outline how you would carry out an experiment to observe mitosis
* **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
How do you set up an eyepiece graticule?
* Line eyepiece graticule + stage micrometer
