Cell Structure + Transport P1 Flashcards
Diffusion
-A net movement of particles from an area of high to low concentration. —> higher the temp, faster the diffusion
-Doesn’t use energy = passive
-Usually results in an equilibrium.
(alveoli to lungs, stomata of leaves)
Osmosis
-A net movement of particles across a partially permeable membrane from an area of high to low concentration
- Doesn’t use energy = passive
-Solute does not cross the membrane (only water).
(root hair cells—> water absorption from soil)
Active Transport
-A net movement of particles from an area of low to high concentration. SUGARS
-Does use energy as particles are moving against the concentration gradient.
(root hair cells, kidneys)
How do you work out the percentage change in mass?
change in mass divided by original mass x 100
Magnification equation triangle/ total magnification equation
I at the top
A on the bottom left, M on the bottom right
(I = image size, A = actual size, M= magnification).
total magnification = eyepiece magnification x objective lens
Cell cycle order (mitosis) + uses
1- DNA replication and cell growth ->chromosomes replicate and so does everything else in cell, line up in centre of cell
2- Mitosis -> chromosomes pulled apart to poles of cell
3- Cell division -> cells and cytoplasm divide to create two genetically identical daughter cells
uses:
- growth
- repair to damaged tissues
- replacement of worn-out cells
Eukaryotes/ic
-Plants and animals
=cells which contain their genetic material enclosed in a nucleus
-0.1-5.0 um
Prokaryotes/ic
-Bacteria
= cells which do not contain their genetic material enclosed in a nucleus
- much smaller
-10 - 100 um (no mitochondria, chloroplasts or nucleus)
Sub-cellular structures
Structure inside a cell
Animal cell’s sub-cellular structure
nucleus, ribosomes, mitochondria, cell membrane, cytoplasm and vacuole
Nucleus
The control centre of the cell which contains chromosomes which contain the cells genetic material.
Cell membrane
Separates the interior from the environment. It is selectively permeable which means it chooses what goes in and out.
Mitochondria
Where aerobic respiration takes place -> requires energy needed for active transport
Cytoplasm
Where chemical reactions occur.
Ribosomes
Responsible for synthesising proteins.
Plant cell’s sub-cellular structure
nucleus, ribosomes, mitochondria, cytoplasm ,cell membrane,
chloroplasts , cell wall and a vacuole.
vacuole
A fluid-filled sac that stores water.
Chloroplasts
Contains chlorophyll, which is needed for the process of photosynthesis.
Cell Wall
Increases the structural strength of the cell as it is made from cellulose
Bacterial Cell’s sub-cellular structure
cell wall, cell membrane, plasmid, cytoplasm and a flagella.
Plasmid
A small ring of DNA.
Flagella
A whip-like structure used for movement.
Cell differentiation/ specialisation
The process where a cell develops new sub-cellular structures to let it perform a specific function.
-when this happens the cell becomes specialised.
Zygote
A single new cell, formed by the fusion of an egg and sperm
Where do embryonic stem cells and adult stem cells come from?
embryonic –> human embryos
adult –> adult bone marrow
Pros and cons of embryonic stem cells
cons:
-unethical as embryo cannot give consent
pros:
-less risk of viral transfer as they divide and grow rapidly
Pros and cons of adult stem cells
cons:
- potential risk of viral infection
pros:
-less ethical objections as full consent can be given
What do plant cells contain that animal cells don’t?
chloroplasts
vacuole
cell wall
Undifferentiated vs partially differentiated
un –> become any type of cell
d –> can only become some types of cells (that they are specialised to)
What 3 factors affect the rate of diffusion?
- temperature of environment
- concentration gradient
- size of particles that are diffusing
Example of diffusion in plants and animals
animals–> gaseous exchange, alveoli in lungs
plants–> stomata in leaves
Sexual Reproduction
Meiosis
- 2 parents needed
- fusion of male and female gametes to create a zygote
- offspring produced is genetically different
- chromosomes are halved (23)
- divides twice
Asexual Reproduction
Mitosis
- involves only one individual
- offspring is genetically identical to parent
- no fusion of gametes
- used for; growth, repair of damaged tissues, replacement of worn out cells
Mitosis
1) nucleus with 46 chromosomes in
2) DNA replication and cell growth;
chromosomes copied (and everything else in cell), nuclear membrane breaks down
3) Mitosis; chromosomes and copies pulled apart and moved towards poles
4) Cell division; cell divides into two genetically identical daughter cells
Gametes
sex cells (egg and sperm)
Root hair cell adaptations
- hairs : long projections which increase the surface area of root to absorb more water and dissolved minerals effectively
- no chloroplasts : root hair cells are underground so cannot carry out photosynthesises, so do not need them
- minerals move into cell by active transport
- water moves into cell by osmosis
Therapeutic Cloning
Transfer of a nucleus from a cell to an egg cell
differentiation
when cells become specialised (adapted to perform a specific function)
Sperm cell job + adaptations
job: join with ovum (egg cell) to fertilise it
adaptations:
- long tail : allows them to swim ( also ‘streamlined@ to make this easier)
- a lot of mitochondria : provide energy for swimming
- contain enzymes : to digest their way through outer layer of ovum
Nerve Cell job + adaptations
job = send electrical impulses around body
adaptations:
- axon : carries electrical impulses covered in ‘myelin’ which insulated axon and speeds up transmission of impulses
- synapses : junctions for impulses to pass from neuron to neuron
- dendrites - increase surface area so other nerve cells can connect easily
Muscle Cell job + adaptations
job = contract muscles ( muscles cells work together to form muscle tissue)
adaptations:
- contain protein fibre : changes the length of cell
- mitochondria : supply energy for muscle contraction
xylem cell job + adaptations
job = found in plant stem/ long tubes which carry water and dissolved minerals from roots to leaves(one way)
adaptations:
-very thick walls containing lignin : provides support
HOWEVER… sealed with lignin so causes xylem cell to die
- end walls between cells which are broken down: so forms a long tube which allows water to flow easily
- no sub cellular structures : easier for water to flow
Phloem Cell job + adaptations
job: carries dissolved sugars up and down
adaptations:
- sieve plates and phloem vessel cells : allows dissolved sugars to move through cell interior
- each phloem vessel cell has a companion cell connected by pores : provides energy to phloem vessel cell as they (phloem vessel cell) have little mitochondria
Factors affecting diffusion
surface area (larger sa the faster the rate of diffusion)
concentration gradient (think of a steep slide = faster diffusion rates)
size of molecule
temperature (more kinetic energy of particles)
distance to travel (shorter diffusion pathway)
how does osmosis effect animal cells?
- dilute/hypotonic (lots of water) making it swell up and burst (lysis)
= why drinking too much is bad
-concentrated/hypertonic(lots of sugar, little h2o) shrivel up (crenation)
biological word for when animal cells burst
lysis
differences between biological words for when animal/plant cells shrivel up?
animal: crenation
plant: plasmolysis/flaccid
how does osmosis effect plant cells?
turgid -
swell up with water(hypo)
plasmolysis/flaccid - shrivel (hyper)
biological word for when plant cells swell up with water?
turgid
hypotonic + leads to
concentration of solutes in solution outside the cell is LOWER than concentration of solutes inside the cell
(lots of water inside cell)
-leads to cells swelling up and bursting of animal cell
animal cells -> lysis
plant cells -> turgid
Hypertonic + leads to
Concentration of solutes in solution outside cell is HIGHER than concentration of solutes inside the cell.
(lots of sugar, little water)
osmosis out of cell
!sugar makes you ‘hyper’!
-leads to cells shrivelling up
animal cells: crenation
plant cells : becomes flaccid (plasmolysis)
isotonic
concentration of solutes inside the cell is the SAME as the concentration of solutes outside the cell (equilibrium)
active transport in cells (uses)
root hair cells -> absorb minerals from soil
small intestine -> glucose in blood
diffusion in cells uses
stomata in leaves
gaseous exchange in alveoli in lungs
blood to body cells (o2 in co2 out)
small intestine
Bacterial Division + equation
-bacteria multiply by simple cell division called binary fission
=carry out binary fission once every 20 mins with enough nutrients and at a stable temperature
= therefore bacterial can increase rapidly
number of bacteria = 2^n —> number of rounds of division
-e.g bacteria divides every 20 mins for 3 hours. calc the number of bacteria present…
3h = 180 mins
180/20 = 9 (number of rounds)
2^9 = 512 or 5.12 x 10^2
How does diffusion happen in animal cells
1) oxygen -> diffuses into cell for respiration by mitochondria, diffuses into cell as there is a high conc of o2 (as oxygen is transported in bloodstream from lungs) outside the cell and a low conc inside
2) carbon dioxide -> oxygen is used to generate energy in respiration which makes co2. High conc on co2 in cell and low conc outside, so co2 diffused out of cell
3) urea -> a waste product which has a high conc inside cell compared to low conc outside of cell, therefore diffused out of cell into plasma and is excreted by kidneys
surface area to volume ratio
amoeba = single celled organism
= have a high surface area for their volume
1) find the surface area of each side (e.g 1mm x 1mm)
2) find total surface area ( times the sa of a side by the number of faces)
3) find the volume
4) simplify (how many times does it go into the other number)
key ideas:
- larger an organism their sa: vol falls sharply
- problem with multicellular organisms is that their sa is not large enough for their vol
How do fish breathe (diffusion, gills, filament adaptations)
- fish get their oxygen from the water passing through their mouth
- then flows over gills where 02 is transported into bloodstream
(GILLS ARE COVERED IN FINE FILAMENTS WHERE GASES PASS IN AND OUT)
1) deoxygenated blood into filament
2) o2 diffused from water into blood
3) oxygenated blood into body
Filament adaptations which increase the efficiency of diffusion:
- massive surface area
- thin membrane = short diffusion pathway
- efficient blood supply = takes 02 blood away ensuring their is always a high concentration gradient for diffusion
dilute vs concentrated solutions
dilute = high concentration of water concentrated = low concentration of water
osmosis in animal cells (put in dilute and conc solutions)
- cytoplasm is concentrated (low water)
dilute:
- water into cell via osmosis (hypotonic)
- cell expands and can burst as no cell wall
concentrated
- water out of cell via osmosis (hypertonic)
- cell shrinks
osmosis in plants cells (put in dilute vs conc solution)
dilute:
- water into cell via osmosis
- cell is swollen (turgid) but does not burst as they have a cell wall which strengthens it
concentrated:
- water out of cell via osmosis
- cell shrivels (flaccid)
RP 3 : effects of osmosis on plant tissue *(Potato)
1) Peel potato as skins can affect osmosis
2) Use a cork borer to make them the same diameter and produce 3 potato cylinders
3) Use a scalpel to trim cylinder into same lengths (3mm)
4) Measure, using a ruler, the length of cylinders , mass measured with balance
5) Place each cylinder into one of three test tubes
1st -> 10cm^3 of 0.5 molar sugar solution
2nd -> 10cm^3 of 0.25 molar sugar solution
3rd -> 10cm^3 of distilled water
6) Leave overnight then remove cylinders and toll them up in paper towels to remove surface moisture (DO NOT squish them as will force water out)
7) Measure length and mass again then calc percentage change
RESULTS :
distilled = potato gains mass via osmosis
molar sugar solution = loses mass via osmosis
Percentage change equation
change in value/ original value x 100
Active Transport in animal and plant cells
1) lumen of small intestines
= low conc of particles outside cell in lumen (so cannot diffuse)
= particles use active transport instead then transport into blood
= a lot of mitochondria as carry out respiration which requires a lot of energy
2) root hair cells
= conc of ions in soil is less than conc of root hair cell so uses active transport
= then transported to xylem into leaves
= a lot of mitochondria asw
