CELLS Flashcards
1
Q
What is the structure and function of the cell surface membrane?
A
- The cell surface mebrane is made up of a phospholipid bilayer
- Each phospholipid has a hydrophobic fatty acid tail which is found on the inner side of the membrane so that cells do not separate out with water and a hydrophyllic phosphate head
- Controls what enters and exits the cell, contains various transport proteins which facilitate the movement of substances in and out of the cell, e.g. carrier and channel proteins
2
Q
What is the structure and function of the nucleus?
A
- nucleolis: production of ribosomes- mRNA and tRNA
- nuclear envelope: double membrane, can contain ribosomes on its surface
- nuclear pores: allows the passage of large molecules in and out of the cell
- nucleoplasm: site for biochemical reactions in the production of ribosomes, also stores ions and molecules
- nuclear membrane: in places iit is continuous and joins twith the endoplasmic reticulum
3
Q
What is the structure and function of the mitochondria?
A
- Cristae: extensions of the inner membrane- increases SA:V ratio
- Matrix: stores proteins, lipids, ribosomes and DNA
- Produces ATP for the generation of energy
- Contains ribosomes to make its own proteins
4
Q
What is the structure and function of chloroplasts?
A
- chloroplast envelope- double plasma membrane
- Grana: stacks of up to 100 disk like structures called thylakoids, thylakoids contain chlorophyll and they have tubular structure which join up with thylakoids in adjacent granas. Granas are the site of light absorption,m the first stage of photosynthesis.
- Granas membranes have large SA for the attachment of chlorophyl, electron carriers and enzymes, for the efficient absorption of light
- Stroma: fluid filled matrix and is the site of sugar synthesis, the second stage of photosynthesis, it contains starch grains for energy and the proteins needed to synthesise sugars
- Chloroplasts contain both DNA and ribosomes so they can manufacture proteins needed for photosynthesis
5
Q
What is the structure and function of the golgi apparatus and golgi vesicles?
A
- A stack of membranes that make up flattened sacs called cristernae with small rounded hollowed shapes called vesicles
- Proteins from the ER are sent here to be modified and labelled, so they can be transported to the right place
- Modified proteins are then transported through vesicles which fuse with the cell membrane to release its contents- exocytosis
- adds carbohydrates to proteins to form glycoproteins
- transport modifies and stores lipids and proteins
- secretes carbohydrates
- forms lysosomes
6
Q
What is the structure and function of lysosomes?
A
- lysosomes are formed when vesicles from the golgi apparatus contain the hydrolytic enzyme lysozyme, which can hydrolyse cell walls
- lysosomes isolate these enzymes before releasing them to phagocytal cells
- Autolysis- completely break down dead celld
- hydrolyse the cell walls of cells that have been ingested by phagocytal cells
- digest worn out cells so their chemicals can be reused
- Release lysozymes to the outside of a cell so that it can destroy whats around it
7
Q
What is the structure and function of ribosomes?
A
- Larger in eukaryotic cells that prokaryotic
- 2 sub units both containing RNA and protein
- site of protein synthesis
8
Q
What is the structure and function of the endoplasmic reticulum?
A
- sheet like mebranes that spread through the cytoplasm of the cell
- Rough ER: has ribosomes on its outer surface. It provides a large SA for the synthesis of proteins and glycoproteins. Also provides a pathway for transporting material especially proteins around the cell
- Smooth ER: lacks ribosomes on its outer surface. It is used for the transport, storage and synthesis of carbohydrates and lipids
9
Q
What is the strusture and function of the cell wall?
A
- Cellulose: Made up of bonds between Beta glucose to form a straight unbroken chain, these chains then bond via hydrogen bonds to form microfibrils and macrofibrils
- Hydrogen bonds provide the cell wall with structural support, which is necessary for keeping the plant cells turgid
10
Q
What is the structure and function of a cell vacuole?
A
- Tonoplast- the mebrane surrounding the vacuole, controls what enters and leaves
- Vacuolar sap: contains water, ions, sugars, enzymes, pigments and waste products
- Keeps the plant upright by maintaining turgor pressure
11
Q
Describe the fluid mosaic model?
A
- movement of the phospholipids and associated protein membranes means that small uncharged molecules can freely enter the cell
- phospholipid bilayer- hydrophobic fatty acid tail and hydrophyllic phosphate head
- cholesterol: when cold stops fatty acid tails sticking together to maintain fluidity, and when too hot stops tails from pulling apart to keep the membrane partially permeable
- Integral proteins: channel proteins and carrier proteins
- polysacharides, glycolipids and glycoproteins necessary for cell signalling/antigens
- Extrinsic protein: anchors to the cykoskeleton to keep it from moving around
12
Q
What is simple diffusion?
A
- net movement of particles down a concentration gradient requiring no external energy. The only particles that can pass throught the phospholipid bilayer via simple diffusion are small and uncharged
13
Q
What affects the rate of movement across cell membranes
A
- surface area- offers opportunity for more proteins on the cell surface membrane
- carrier and channel proteins- affects the rate of facillitated diffusion
- gradients and water potential- affects the rate of diffusion
14
Q
What is facillitated diffusion(deeply)?
A
- carrier proteins bind to specific molecules, causing its shape to change and the molecules to be released on the other side of the membrane.
- Channel proteins are water filled pores which span the membrane they allow the transport of specific molecules, depending on size property and charge.
- The maximum rate occurs when all proteins are in use.
15
Q
What is osmosis?
A
- the net movement of water particles down a concentration gradient through a partially permeable membrane
