cell structure + function Flashcards
1
Q
Prokaryotic cells
A
- Kingdoms Eubacteria & Archaeobacteria
- Simple cells
- No membrane bound organelles (including a nucleus)
- Circular chromosome
2
Q
Eukaryotic cells
A
- Kingdoms Protista, Fungi, Animals & Plants
Complex cells - Have membrane bound organelles & a membrane bound nucleus
- Linear chromosomes in a nucleus
- All contain mitochondria, some have chloroplasts
- Mitochondria and chloroplasts have DNA.
3
Q
Plasma membrane
A
the layer of membrane forming the outer layer of the cell
4
Q
Nuclear membrane
A
the layer of membrane separating nucleus from rest of cell
5
Q
Nucleoplasm
A
material inside nuclear membrane
6
Q
cytoplasm
A
everything in between the plasma membrane and nuclear membrane (cytosol and organelles
7
Q
cytosol
A
liquid part of the cytoplasm
8
Q
vesicle
A
a bubble of membrane used for the transport of materials and sometimes for temporary storage
9
Q
mitochondria
A
- The site of aerobic cellular respiration
- Provides energy to the cell in the form of ATP (adenosine triphosphate)
- Double membrane organelle
- Inner membrane has folds called cristae
- Inner spaces are fluid filled and are called matrix.
- Contain their own circular DNA & ribosomes
10
Q
chloroplasts
A
- Found in some plant and protist cells
-Responsible for photosynthesis - Double membrane organelles
- Internal structure consists of stacks of membranes called grana (granum)
- Each individual membrane in a stack is called a thylakoid
- Grana are joined by lamellae (lamella)
- Fluid called stroma fills any empty spaces
- Contain their own DNA & ribosomes
- Contain chlorophyll
11
Q
ribosomes
A
- found in both prokaryotes & eukaryotes
- Ribosomes of chloroplasts and mitochondria are chemically similar to bacterial ribosomes.
- made of RNA and do not have a membrane
- found in cytosol or on ER
-responsible for constructing proteins from amino acids
-body can make mot amino acids
-needs 20 from diet
12
Q
Endoplasmic reticulum (ER)
A
- Transports materials around cell
- Rough ER studded with ribosomes, modify and transports proteins
- Smooth ER lacks ribosomes but do sometimes transport proteins
- Smooth ER; synthesis & transport of lipids, including steroid hormones
- Some substances are transported from the ER to the Golgi Apparatus in vesicles
13
Q
Golgi apparatus/body/complex
A
- System of flattened sacks of membrane, called cisternae (cisterna)
- Responsible for final modification of proteins
- Packages materials to be secreted into vesicles
- Vesicles fuse with the plasma membrane and release their contents (secrete) outside of the cell by exocytosis (more about this later).
14
Q
Vacuole
A
- Sacks of membrane used to store materials inside cells
- in animals are small, many and usually temporary
- in plants are large, permanent and there is usually only one of them.
- Plant vacuoles are used to store water and water soluble substances such as proteins and minerals
- When plant vacuoles fill with water they push the cytoplasm hard up against the membrane
15
Q
Lysosomes
A
- Double membrane organelles
- Contain digestive enzymes
- Only found in animal cells
16
Q
Plastids
A
- responsible for containing, & synthesizing, coloured pigments
- Include leucoplasts (white) which are primarily responsible for starch storage, along with some protein or fat
- Chromoplasts which give flowers their colour, contain yellow, orange or red pigments
- Chloroplasts, responsible for photosynthesis, contain green chlorophyll
17
Q
Cytoskeleton
A
- structure of fibres made of microtubules and microfilaments which gives the cell shape and form
- Microtubules are made of a protein called tubulin
- Microtubules form the spindle during cell division and the centrioles of animal cells
- Microtubules also form the cilia and flagella that allow some cells to move
- Microfilaments are made of actin
- Actin is stretchy. It allows muscle cells to contract
- Allows movement of organelles inside the cell; including cytoplasmic streaming.
18
Q
Cell wall
A
- Plants, fungi, most bacteria and some protists have cell walls
- Fungal cell walls are made of chitin
- Bacterial cell walls are made of murein (a peptidoglycan)
- Plant cell walls are made of cellulose.
- Cell walls of protists are very varied in chemistry.
- Cell walls provide support and stop cells expanding too much.
19
Q
Compartmentalisation
A
Many of the organelles in cells form compartments
Conditions in different compartments can be different in pH, concentration and chemical make up.
Advantages of compartmentalisation:
- Enzymes and reactants can be close together and in the ideal conditions
- Different processes which require different conditions can all take place at the same time in the cell
- The cell is more able to withstand environmental changes
20
Q
surface area to volume ratio
A
- limit on how large cells can be.
- If cells get too large exchange of materials becomes too slow for life
- Size is limited by the rate of diffusion
- Volume increases faster than surface area.
21
Q
plasma membrane
A
- described by the Fluid Mosaic Model
- phospholipid bilayer with embedded proteins and cholesterol.
22
Q
phospholipids
A
- consist of a phosphate head and fatty acid tail
The phosphate head is hydrophilic (water loving) - fatty acid tails are hydrophobic (water hating)
- Hydrophilic = lipophobic
- Hydrophobic = lipophilic
23
Q
protein channels
A
- fixed in the membrane
- a ‘pipe’ through which materials can travel between the interstitial fluids and the cytosol
- Molecules do not attach to the channel, they move through the middle
- Carry ions and other water-soluble materials
24
Q
carrier proteins
A
- can flip so materials can be collected on one side of the membrane and be released on the other.
- Molecules to be carried attached to the protein for carriage
- Transport both water-soluble and lipid-soluble molecules
25
receptors
- docking stations for signaling molecules like neurotransmitters and hormones
- Some are attached to protein channels where the signaling molecule makes the channel open or close
26
cholesterol
- prevents phospholipids from packing together too closely.
- maintains fluidity.
- role of the cholesterol is closely linked to temperature.
- At high temp: it stops the membrane from becoming too fluid as it restricts the lateral movement of the molecules.
- At low temp: it prevents membranes from freezing as it stops the molecules packing too tightly
27
crossing the membrane
plasma membrane = partially/selectively/differentially permeable.
Substances cross the membrane by:
- Diffusion
- Facilitated diffusion
- Active transport
- Endo/exocytosis (bulk transport)
28
diffusion
- movement of molecules from and area of high concentration to an area of low concentration
- Lipid soluble and small uncharged molecules cross the membrane by simple diffusion
- Water is a solvent it does NOT have a concentration
29
osmosis
movement of water from a dilute solution to a concentrated solution
30
facilitated diffusion
- Moves molecules down concentration gradients
- Uses carrier molecules or protein channels
- Large molecules, polar molecules & some ions
- Glucose enters cells through facilitated diffusion using a carrier protein
31
Active transport
- Moves substances against the concentration gradient
- Requires energy
- Uses protein channels and carrier proteins
- Results in the movement of large & charged atoms, ions and molecules
32
Endocytosis
- movement of substances into a cell through the formation of vesicles
- Requires energy
Pinocytosis – intake of liquids
Phagocytosis – intake of solids
33
Exocytosis
- movement of substances out of a cell
- formation of vesicles which fuse with the plasma membrane
- Requires energy
