1
Q
what is the structure of the nucleus?
A
- has a double membrane, the nuclear envelope which contains pores which allows substances like RNA through
- nucleolus does not have a membrane, it contains RNA
- contains chromatin, DNA wound around histone proteins. the chromatin is the nucleoplasm
2
Q
what is the function of the nucleus?
A
- site of DNA replication and transcription
- nuclear envelope separates the contents of the nucleus from the rest of the cell
- contains nearly all of the genetic material, contains instructions for making proteins/genetic code
- RNA can leave nucleus through pores in nuclear envelope
- nucleolus is where ribosomes are made
- chromosomes contain organisms genes
3
Q
what is the structure of mitochondria?
A
- 2.5um long
-double membrane
-inner membrane is folded into a cristae
-middle space between membranes is filled with fluid called the matrix
4
Q
what is the function of mitochondria?
A
- site of ATP production during aerobic respiration
- have own DNA, ribosomes so can create enzymes for respiration inside organelle
- abundant in cells where much metabolic energy is needed
5
Q
what is the structure of chloroplasts?
A
- large organelles
- only in plant cells
- double membrane
- contain stacks of flattened membrane sacs called thylakoids which contain chlorophyll, each stack of thylakoids is called a grana
- contains the liquid called stoma which contains enzymes, lipids, starch, ribosomes, loops of DNA
6
Q
what is the function of chloroplasts?
A
- site of photosynthesis
- light energy I strapped by chlorophyll and used to make ATP this occurs in the grana
- uses energy from ATP to make carbohydrates occurs in stoma
- chloroplasts are abundant in leaf cells particularly the palisade mesophyll layer
7
Q
what is the structure of the rough endoplasmic reticulum?
A
- network of membranes formed of flattened sheet like sacs called cisternae
- coated with ribosomes
- appears as pairs of parallel lines running through cytoplasm
8
Q
what is the function of rough endoplasmic reticulum?
A
- intracellular transport system: the cisternae form channels for transporting substances
- provides a large surface area for ribosomes to make amino acids into proteins
- transports and modifies ribosomes
9
Q
what is the structure of the smooth endoplasmic reticulum?
A
- system of folded membranes called cisternae
- no ribosomes
10
Q
what is the function of the smooth endoplasmic reticulum?
A
- contains enzymes involved in lipid synthesis
- transport and absorption of lipids
11
Q
what is the structure of the Golgi apparatus?
A
- stack of membrane bound flattened sacs making cisternae
- secretary vesicles pinch off from the cisternae
12
Q
what is the function of the Golgi apparatus?
A
- modifies proteins for example:
adding sugar molecule to make glycoproteins and being folded into their 3D shape - transports proteins by pinching them of in vesicles
- form lysosomes
13
Q
what is structure of a lysosomes?
A
- formed from golgi apparatus
- single membrane
- contain hydrolytic digestive enzymes
14
Q
what is the function of lysosomes?
A
- engulf old cell organelles
- exocytosis
15
Q
what is the structure of cilia?
A
- hairlike projections out of cells
- contains microtubules
- formed from centrioles
16
Q
what is the function of cilia?
A
- waft substances
- detect signals
17
Q
what is the structure of vacuole?
A
- surrounded by membrane called tonoplast
- contains fluid
18
Q
what is the function of vacuole?
A
- maintains cell stability
- makes cell turgid
19
Q
what is the structure of centrioles?
A
- 2 bundles of microtubules at right angles
- microtubules are made of tubulin
- occur in pairs to form a centrosome
20
Q
what is the function of centrioles?
A
- involved in the production of spindle fibres
- involved in formation of cilia
21
Q
what is the structure of cytoskeleton?
A
- a network of fibres within cytoplasm
- consists of microfilaments, microtubules and intermediate fibres
- cytoskeletal motor proteins, allows hydrolysis of ATP to produce energy
22
Q
what is the structure of ribosomes?
A
- small
- made of 2 sub units of protein and RNA
- 80s found in eukaryotic cells
- 70s found in mitochondria, chloroplasts and prokaryotic cells
23
Q
what is the function of ribosomes?
A
- protein synthesis
24
Q
what is the structure of the cell wall?
A
- plant: made of bundles cellulose fibres
- fungi: made of chitin
25
what is the function of the cell wall?
- prevents cell bursting, keep cell turgid
- prevent strength and support
- maintain cell shape
- permeable
26
what is the magnification of a light microscope?
X1500
27
what is the resolution of a light microscope?
0.2um
28
what is the magnification of a SEM?
x200,000
29
what is the resolution of a SEM?
1 nm
30
what is the magnification of a TEM?
x million
31
how are proteins made and secreted?
1. gene contain instructions which are transcribed into length of RNA called mRNA
2. many copies of the mRNA are made and pass out of nuclear envelope to the ribosomes
3. at ribosomes the instructions are translated and protein molecules are assembled
4. pass into RER
5. vesicles from RER to Golgi apparatus
6. vesicles fuse to Golgi apparatus where it is modified
7. vesicles pass to plasma membrane
8. Vesicle and plasma membrane fuse and protein is released
Biology: 2.1 Cell Structure
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