Chapter B1 Cell Structure and transport Flashcards
what is the maximum magnification and resolving power of light microscopes?
x2000, 200 nm
what is the maximum magnification and resolving power of electron microscopes?
x2000000, 0.2 nm
magnification =
size of image / size of real object
animal cell structures and functions
- nucleus: controls all activities of cell, surrounded by nucleus membrane.
- cytoplasm: liquid gel where organelles are suspended, chemical reactions take place.
- cell membrane: controls passage of substances in and out of cell.
- mitochondria: aerobic respiration takes place, releasing energy for cell.
- ribosomes: protein synthesis takes place
average diameter of a nucleus
10um
size of mitochondria
1-2um in length, 0.2-0.7um in diameter
plant cell structures and functions
- nucleus
- cytoplasm
- ribosomes
- cell membrane
- mitochondria
- chloroplasts: chlorophyll absorbs light for photosynthesis.
- permanent vacuole: keeps cell rigid to support plant
- cell wall: strengthens cell, gives support
chloroplasts size
3-5um long
resolution meaning
clarity of the image
Eukaryotic examples
animal and plant cells
Eukaryotic structures
- cell membrane
- cytoplasm
- genetic material in nucleus
Prokaryotes example
bacteria (single-celled living organisms)
Prokaryotes structures and functions
- genetic material
- cytoplasm
- cell membrane
- slime capsule
- cell wall
- plasmids (small rings of DNA)
- flagella
flagella function
long protein strand that lashes about, help move themselves about
Prokaryotes size
0.2-2.0um in length, 1-2 orders smaller then Eukaryotes
milli- symbol, 1000^m, 10^n, decimal
m, 1000^-1, 10^-3, 0.001
micro- symbol, 1000^m, 10^n, decimal
u, 1000^-2, 10^-6, 0.000001
nano- symbol, 1000^m, 10^n, decimal
n, 1000^-3, 10^-9, 0.000000001
sperm cells structures and functions
- tail: helps move
- mitochondria: energy
- acrosome: stores digestive enzymes for, breaking down outer layer of the egg
nerve cells structures and functions
- dendrites: to make connections with other nerve cells
- axon: carries the nerve impulse from one place to another
- synapse: pass impulses using special transmitter chemicals
- mitochondria: energy for transmitter chemicals
muscle cells structures and functions
- special proteins: fibres contract
- mitochondria: energy for chemicals reactions as cells contract and relax
- glycogen: cellular respiration
root hair cells structures and functions
- increased surface area: water to move into cell
- large permanent vacuole: speeds up movement of water by osmosis
- mitochondria: energy needed for active transport of mineral ions into the cell
xylem cells structures and functions
-lignin spirals and hollow tube of xylem: makes them strong and help them withstand pressure of water moving in the plant. help support plant stem
phloem cells structures and functions
- cell wall: break down to form special sieve plates, so water moves freely
- companion cells: helps keep them alive
- mitochondria: energy needed to move dissolved food up and down plant phloem
diffusion
the spreading out of particles of any substance, in solution or gas, resulting in a net movement from an area of higher concentration to an area of lower concentration, down a concentration gradient.
what is the rate of diffusion affected by?
- difference in concentrations
- temperature
- available surface area
what dissolved substances move in and out of cells by diffusion?
glucose and urea
what gases move in and out of cells by diffusion?
oxygen and carbon dioxide
osmosis
movement of water from a dilute solution to a more concentrated solution
maximising the rate of diffusion for short distances
- distance between high concentration and the low concentration
- shorter the distance, quicker the rate of diffusion
- net movement by diffusion will be quite slow. particles moving into an area of lower concentration by random movement will be slightly more than particles that are leaving the area
maximising the rate of diffusion for large surface areas
- larger the surface area the more area it gives for particles to go through
- area can increase by folding up the membrane of the cell, or the tissue lining an organ
maximising the rate of diffusion for steep concentration gradients
- bigger difference in concentration, quicker diffusion will take place
- small difference- net movement by diffusion will be slow.
- bigger the difference, steeper concentration gradient
- diffusion occurs down the concentration gradient
net movement=
particles moving in - particles moving out
active transport
- moves substances against the concentration gradient
- uses energy from respiration
- cells that carry out active transport have many mitochondria
examples of active transport
- plant root hairs absorb minerals from dilute solutions in soil
- glucose molecules are absorbed from low concentration in the gut
for substances to exchange effectively they need:
- a big surface area
- small diffusion distance
- steep concentration gradient
diffusion and osmosis (down the concentration gradient):
- passive
- no energy required
active transport (against the concentration gradient):
- active
- energy required from respiration
- many mitochondria are found
- steep concentration gradient isn’t as important for active transport
what happens when living organisms get bigger and more complex?
surface area to volume ratio gets smaller
how to increase the effectiveness of an exchange surface?
-large surface area
-thin membrane or being thin for short diffusion path
In animals:
-efficient blood supply, steeper concentration diffusion gradient
-being ventilated, maintains steep concentration gradients
how does organisms getting bigger negatively affect the speed of which materials exchange?
- gases and food molecules can no longer reach every cell inside the organism by simple diffusion
- metabolic waste cannot be removed fast enough to avoid poisoning the cells
details of microscopy practical
Use a light microscope to observe, draw & label cells.
details of osmosis practical
Investigate the effect of a range of concentrations of solutions on the mass of plant tissue.
microscope labels
- eye piece lens
- stage clips
- fine focusing knob
- light
- objective lens
- stage
- focusing knob
- light switch
what process takes place in mitochondria? word equation, 2 things needed, 2 waste products, purpose and use of product of this process.
- aerobic respiration
- sugar + oxygen -> carbon dioxide + water +energy released
- oxygen + sugar
- carbon dioxide + water
- releases energy for the cell
- energy helps the cell perform work
where do you find genes?
nucleus, chromosomes
what do genes do?
carry the instructions for making the proteins needed to build new cells or new organisms
what are proteins made of?
chain of amino acids
examples of proteins
keratin, collagen, elastin, insulin
