Different parts of a cell is called...
subcellular structures
What do cells make...
everything
Which cell is bigger? Prokaryotic or eukaryotic?
Eukaryotic
What does the cell membrane do?
controls what goes in and out of the cell
What does the nucleus do?
It contains genetic material and controls the activities of the cell
What does the ribosome do?
protein synthesis
What does the mitochondria do?
aerobic respiration
What does the cytoplasm do?
Where most chemical reactions take place
Cellulose cell wall
Gives support and strength
Chloroplasts
photosynthesis, contains chlorophyll
Permanent vacuole
Contains cell sap
Bacteria cells contain...
no nucleus
no chloroplasts or mitochondria
cytoplasm
cell wall (murein)+ membrane
plasmids
What does a nucleoid DNA do?
Holds DNA and genetic information
What is pili?
Short hair-like structures that helps movement
What is a flagellum?
Long tail that enables movement
1mm to um
1000um
1um in nm
1000nm
1cm to um
10000um
light microscope
uses light and lenses to form an image of a specimen and magnify it
electron microscope
-uses electrons to form an image of a specimen and can magnify it to a much higher resolution and magnification
- can be used to study cells in finer detail
- see/ understand many more subcellular structures
Formula for magnification
Magnification = image size / real size
Magnification
How many times bigger the image is than the actual specimen
Resolution
The ability to distinguish between two separate points/how much detail it shows
Why do cells have different structure?
To suit their different functions
Differentiation
-The process by which a cell changes to become specialised
- as an organism develops, cells differentiate to form different types of cells
- animal cells differentiate at an early stage
- plant cells retain the ability to differentiate throughout life
- acquires different subcellular structures to carry out a certain function
Specialisation
The adaption of an organism/cell to a special function or environment
Growth
- a permanent increase in size of an organism because of cell division or enlargement
- little to no growth in mature animals
- growth occurs in plants throughout their lifetime
- restricted in meristems
sperm cell- a long tin tail
helps with movement to swim fast to the egg
sperm cell-streamlined head
aerodynamic helps it swim to the egg
Sperm cell - lots of mitochondria
provides energy for movement
Sperm cell- special lysosome(acrosome)
releases enzymes for breaking through the membrane
Sperm cell- large nucleus
carries half of the genetic material
Nerve cells function
carries electrical signals from one play to the other
Nerve cell- lots of dendrities
allows connection with other nerve cells
Nerve cells axon
carries impulse from one place to other
Nerve cell lots of mitochondria
Makes the transmitter chemical
Nerve cell: Synapse(nerve ending)
passes the impulse to other cells
muscle cell function
to contrast and relax
muscle cell special proteins
slide over one another, allowing contraction
muscle cell lots of mitochondria
energy for contraction
Root hair cells function
Absorbing water and minerals ions from soil
root hair large surface area
can absorb the most out of the soil
root hair large vacuole
speeds up osmosis
Root hair lots of mitochondria
provides energy for active transport
Phloem and xylem cells function
Transporting substances
Phloem and xylem hollow tubes
substances can flow through them easily
Culturing Bacteria
- bacteria multiple by cell division (binary fission) every 20 mins if they have enough nutrients and suitable temperature
- can be grown in a nutrient broth solution
- or as colonies on an agar gel plate
uncontaminated cultures
- required to investigate action of disinfectants and antibiotics
- To sterilize petri dishes and culture medium heat at high temperature.
- Pass inoculating loop through hot flame.
- Lid stored upside down to stop condensation from falling onto the agar, secured with adhesive tape
- cultures incubated at 25 C
Chromosomes
- contained in the nucleus
- made of DNA molecules
- each carries a large number of genes
- found in pairs (body)
What is the cell cycle?
series of stages where cells divide
cell cycle stage 1
- grows/increases number of subcellular structures (ribosomes/ mitochondria)
- DNA replicates to form two copies of each chromosome
cell cycle stage 2
-mitosis
- one set of chromosomes is pulled to each end of the cell
- the nucleus divides
Why/ when is mitosis important?
- growth
- repair damaged tissue
- asexual reproduction
- replaces worn out cells
- development of multicellular organisms
cell cycle stage 3
cytoplasm and cell membranes divide to form two identical cells
stem cells
an undifferentiated cell of an organism which is capable of division to produce many more cells of the same type
- from which certain other cells can be produced by differentiation
embryonic stem cells
- found in embryos
- cloned and made to differentiate into most different types of human cells
adult stem cells
- remaining stem cells in the adult
- can form many types of cells
- e.g bone marrow- blood cells
meristem tissue in plants
- can differentiate into any type of plant cell
throughout the life of the plant
treatment with stem cells
- helps with conditions such as diabetes and paralysis
therapeutic cloning
- an embryo is produced with the same genes as the patient
- stem cells from the embryo aren't rejected by the patient's body
- may be used for medical treatment
cloning plants
- production fo genetically identical plants
- tiny piece of plant tissue taken and with the right conditions
- cells become unspecialised and undergo rapid cell division involving mitosis to produce a ball of cells
- quickly and economically
- rare species can be cloned to protect from exxtinction
- crop plants w/ special features can be cloned to produce larger number of identical plans for farmers
- e.g disease resistance
advantages of stem cells
- plentiful supply
- painless technique
- can treat many diseases e.g cancer, diabetes
- adult stem cell can become any type of cell
disadvantages of stem cells
- unethical can cause harm to embryo
- embryo has no consent/ right to life
- unreliable
- cells might transfer a virus
- may be rejected
- patient has to take immunosuppressant drugs
advantages of adult stem cells
- adult can give permission
- can treat some diseases
- less chance of rejection
- technique is reliable
disadvantages of adult stem cells
- risk of infection
- can only treat a few diseases
- procedure to remove can be painful
Diffusion
- spreading out of the particles of any substance in solution/ particles of a gas
- net movement from an area of higher concentration to an area of lower concentration
what are some substance transported by diffusion?
- oxygen
- carbon dioxide in gas exchange
- the waste product urea from cells into the blood plasma for excretion in kidney
Where does diffusion happen?
Solutions and gases because they are free to move about randomly
Dissolved substances can...
Move in and out of cells by diffusion
What can move through the Cell membrane?
very small molecules- oxygen, amino acids and water
What can't move through the cell membrane
Bigger molecules like starch and protein
Molecules move randomly so...
they go both ways but if theres a lot more particles on one side then theres a net movement from that side
Affects the rate of diffusion- difference in concentration
The larger the concentration gradient the faster the rate of diffusion down a concentration gradient
Affects the rate of diffusion- temperature
Higher the temperature, faster the rate of diffusion
affects rate of diffusion- surface are of membrane
Larger the surface area, the faster the diffusion
affects rate of diffusion- diffusion distance
Shorter the distance, faster the rate of diffusion
e.g single celled organism
- relatively large surface area to volume ratio
- allows sufficient transport of molecules into and out of the cell to meet the needs of the organism
exchange surfaces
- increasing size = smaller surface area:volume ratio
- cells no longer reach every cell by simple diffusion
- sufficient molecules to be transported into and out of cells for the organism's needs
exchange surface adaptions
- effectiveness increased
- larger surface area
- thin membrane to provide short diffusion path
- (animals) efficient blood supply to move diffusing substances awat and maintain a concentration gradient
- (animals, for gaseous exchange) being ventilated to maintain steep concentration gradient
exchange in the gut-villi = exchange surface
- food molecules like glucose, amino acids, fatty acids and glycerol must be moved from inside your small intestine into your bloodstream- absorption
- diffusion and active transport
-small intestine covered in millions of villi
-they provide large surface area so digested food absorbed quickly into blood
-have single layer of surface cells- short path
-good blood supply to maintain conc gradient- blood capillaries
Osmosis
- movement/ diffusion of water from an area of high concentration of water (dilute) to an area of low concentration of water (concentrated) through a partially permeable membrane that allows the passage of water molecules
Examples of osmosis
red blood cells
dilute
high water concentration
if a plant cell is too dilute
it becomes turgid
if a plant cell is too concentrated
it becomes plasmolysed
active transport
movement of substances into cells from a low concentration to a high concentrated solution against a concentration gradient, requires a protein pump and energy from respiration across a membrane
active transport- root hairs
- allows mineral ions to be absorbed into plant root hairs from very dilute solutions in the soil
- plants require ions for healthy growth
active transport- sugar
- allows sugar molecules to be absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration
- sugar molecules are used for cell respiration