2.1.1 G) Ultrastructure of Eukaryotic Cells + Functions of Dif. Cellular Components Flashcards
1
Q
Organelles:
A
- parts of cells
- each has a specific function
2
Q
Cell ultrastructure:
A
when you examine a cell through an electron microscope you can see its organelles and the internal structure of most of them
3
Q
How are plant cells different to animal cells?
A
- a cell wall with plasmodesmata (’channels’ for exchanging substances between adjacent cells)
- a vacuole - compartment that contains cell sap
- chloroplasts - the organelles involved in photosynthesis
4
Q
Diagram + components of animal cell:
A
- nucleus - nucleolus, nuclear membrane
- lysosome
- cell surface membrane/plasma membrane
- Golgi apparatus - vesicles
- rough endoplasmic apparatus (RER)
- smooth endoplasmic apparatus (SER)
- centrosome
- cytoplasm
- ribosomes
5
Q
Diagram + components of plant cell:
A
- nucleus - nucleolus, nuclear membrane
- lysosome
- cell surface membrane/plasma membrane
- Golgi apparatus - vesicles
- rough endoplasmic apparatus (RER)
- smooth endoplasmic apparatus (SER)
- centrosome
- cytoplasm
- ribosomes
- vacuole
- chloroplast
- cell wall
6
Q
Where is the cell surface membrane/plasma membrane found?
A
found on the surface of animal cells and just inside the cell wall of plant cells and prokaryotic cells
7
Q
What is the cell surface membrane/plasma membrane made of?
A
made of mainly lipids and proteins
8
Q
Function of cell surface membrane/plasma membrane:
A
- regulates transport of substances in and out of the cell
- sites of cell communications (cell signalling)
- may release chemicals that signal to other cells
- contains receptors for such chemical signals and so is a site for cell signalling - hormones and drugs may bind to receptors in the membranes
- may be sites of chemical reactions
- partially permeable barriers between the cell and its environment, between organelles ad the cytoplasm and within organelles
- may contain enzymes involved in specific metabolic pathways
- has antigens so the organism’s immune system can recognise the cell as being ‘self’ and not attack it
9
Q
Where is the cell wall found?
A
a rigid structure found on the outside of the plasma membrane that surrounds plant cells
10
Q
Function of cellulose cell wall:
A
- Provide strength and support plant cells
- Maintain cell shape
- Prevent cell bursting
- Is permeable to solutions to pass through
11
Q
What is the cell wall mainly made of?
A
Made of fibres of a carbohydrate polysaccharide – cellulose
12
Q
Diagram of nucleus:
A
13
Q
Describe the structure of the nucleus:
A
- large organelle surrounded by a nuclear envelope (double membrane)
- the envelope has pored to allow certain substances to move in and out of the nucleus
14
Q
What does the nucleus contain?
A
- the nucleus contains chromatin (which is made from DNA and proteins)
- and often contains a structure called the nucleolus
15
Q
What does the nucleolus contain and what is its function?
A
- nucleolus contains RNA
- it is where ribosomes are made
- does not have a membrane around it
16
Q
Function of nucleus:
A
- Control cells activities - by controlling the transcription of DNA
- Stores organism’s genome
- Transmits genetic information - the pores allow substances (e.g. RNA) to move between the nucleus and the cytoplasm
- Provides the instructions for protein synthesis
- Nucleolus makes ribosomes
17
Q
What are lysosomes made by?
A
made by the Golgi apparatus
18
Q
Describe the structure of lysosomes:
A
- round organelle
- surrounded by a single membrane
- no clear internal structure
19
Q
Function of lysosomes:
A
- contains powerful hydrolytic (digestive enzymes) - kpt separate from the cytoplasm by the surrounding membrane
- abundant in phagocytic cells - lysosomes help to digest invading cells/pathogens or to break down work out components of the cell
20
Q
Diagram of lysosome:
A
21
Q
How large are ribosomes?
A
approx. 20nm in diameter
22
Q
What is the structure of ribosomes?
A
- made of 2 subunits - large subunit and small subunit
- not surrounded by a membrane
23
Q
What are ribosomes made up of?
A
ribosomes and RNA
24
Q
Where are ribosomes found?
A
- attached to the rough endoplasmic reticulum (RER)
- found floating free in the cytoplasm
25
Function of ribosomes on RER:
synthesises proteins that will be exported out of the cell
26
Function of free floating ribosomes in the cytoplasm:
synthesises proteins that will be used within the cell
27
Describe the structure of rough endoplasmic reticulum (RER):
- system of cisternae (membranes)
- covered in ribosomes → large surface area
- continuous with the nuclear membrane - substances can be transported to other parts of the cell
28
Function of rough endoplasmic reticulum (RER):
- folds and processes proteins that have been made at the ribosomes
- substances can be transported to other parts of the cell. e.g proteins made on the ribosomes can be packaged into vesicles and transported to the Golgi apparatus
29
Diagram of rough endoplasmic reticulum (RER):
30
Describe the structure of smooth endoplasmic reticulum (SER):
- system of cisternae (membranes)
- not covered in ribosomes
- continuous with the nuclear membrane
31
Diagram of smooth endoplasmic reticulum (SER):
32
Function of the smooth endoplasmic reticulum (SER):
- involved in lipid metabolism (synthesis of cholesterol, steroid hormones and phospholipids)
- synthesises and processes lipids
33
Where are vesicles found?
often seen at the edge of the sacs (Golgi apparatus)
34
Function of vesicles:
- once processed by the Golgi apparatus, proteins are packaged (by the GA) into secretory vesicles that are either stored in the cell or move to the plasma membrane
- secretory vesicles move along the cytoskeleton using motor proteins – ATP needs to be broken down to do this
- transports substances in and out of the cell (via the plasma membrane) and between organelles
35
Where and by what are vesicles formed?
- some formed by the Golgi apparatus or the endoplasmic reticulum
- others formed at the cell surface
36
Diagram of vesicles:
37
Describe the structure of Golgi apparatus:
a stack of membrane bound, fluid-filled, flattened sacks
38
Function of Golgi apparatus:
- modifies, processes and packages new lipids and proteins - modification via:
- adding sugar to make a glycoprotein
- adding lipid to make lipoprotein
- being folded into a 3D shape
- makes lysosomes
39
Diagram of Golgi apparatus:
40
How long are mitochondria?
approx. 2-5μm long
41
Describe the structure of mitochondria:
- usually oval-shaped
- double membrane structure - inner is highly folded into cristae
- inner part is fluid filled matrix which contains enzymes involve din respiration
42
Function of mitochondria:
site of ATP production during aerobic respiration
43
Where are mitochondria most abundant?
Most abundant in cells where there is high metabolic activity, e.g. muscle and liver cells
44
How do mitochondria replicate?
self-replicating
45
Diagram of a mitochondrion:
46
Describe the structure of chloroplasts:
- small flattened structure found in plant cells
- surrounded by double membrane - inner and outer
- contains stacks of flattened membranes called thylakoids - contain chlorophyll *(resembles stack of plates)*
- Plate = thylakoid, Stack = granum
47
How long are chloroplasts?
around 4-10μm long
48
Function of chloroplasts:
- site of photosynthesis
- inner membrane contains a fluid called stroma that contains enzymes needed for photosynthesis
- contains starch grains to provide energy for photosynthesis
49
Where does the photosynthesis in chloroplasts take place?
some parts of photosynthesis happen in the grana and other parts happen in the stroma (thick fluid found in chloroplasts)
50
Diagram of chloroplasts:
51
What is the vaculoe surrounded by?
Surrounded by a membrane called the tonoplast
52
Function of a vacuole:
Fluid filled (water and solutes) to maintain cell stability and turgidity
53
Describe the structure of centrioles + what are centrioles made of?
- small hollow cylinders
- made of microtubules (tiny protein cylinders)
54
Where are centrioles found?
- found in animal cells but only some plant cells
- usually absent from cells of larger, complex plants but present in simple unicellular green algae
55
How are centrioles found?
Found in pairs – one at a right angle to the other
56
Function of centrioles:
- involved in the production of spindle fibres used in cell division so involved in separation of chromosomes in cell division
- involved in the formation of cilia and undulipodia
57
Diagram of centrioles:
58
Describe the structure of cilia:
- small, hair-like structures found on the surface membrane of some animal cells
- in cross-section they have an outer membrane and a ing of 9 pairs of protein microtubules inside, with a single pair of microtubules in the middle
59
Where are cilia found?
found on the surface membrane of some animal cells
60
What are cilia made of?
centrioles
61
Function of cilia:
- cilia line airways to waft/beat mucus - the microtubules allow the cilia to move, the movement is used by the cell to move substances along the cell surface
- nearly all cells have at least one cilium that acts as an antenna/receptor for the immediate environment
62
Diagram of cilia:
63
Describe the structure of flagella:
- flagella on eukaryotic cells are like cilia but longer
- they stick out fom the ell surface and are surrounded by the plasma membrane
- inside they contain 2 microtubules in the centre and 9 pairs around the edge
64
Function of flagella:
- the microtubules contract to make the flagellum move
- flagella are used like outboard motors to propel cells forward
65
Diagram of flagella:
