CELLS PAPER 1 Flashcards
What are eukaryotic cell and its different structures?
eukaryotic cells are membrane bound organelles
structure:
- cell membrane
- cell wall ( plant cells)
- nucleus:
nuclear pore for substances to enter and leave, nuclear envelope to separate nucleus from cytoplasm nucleolus synthesis of ribosomes
- soft endoplasmic reticulum- no ribosomes synthesis of lipids and phospholipids
-rough endoplasmic reticulum- ribosomes for protein synthesis
-Golgi apparatus- packages and processes lipids, phospholipids and proteins.
golgi vesicles- transports substances around the cell
- lysosomes are vesicles which release hydrolytic enzymes which digest cell debris/ bacteria
- cytoplasm- surrounds organelles, cytosol is the liquid part
- vacuole- holds cell sap, tonoplast is the membrane
- chloroplast- 70S ribosomes, thylakoid- contains chlorophyll, matrix inside the fold grant is the discs of thylakoid, storm is the fluid that surrounds the structures like the cytoplasm
- mitochondria- cristae is the fold which increases surface area for aerobic respiration
- ribosomes- made of a smaller subunit and a larger sub unit which synthesises proteins
What are prokaryotic cells and its structures?
prokaryotes are not membrane bound organelles
prokaryotes are much smaller than eukaryotes
-slime capsule:
prevent desiccation, stop enzymes digesting, sticks cells together
- cell wall- made of murein
- nucleoid- contains dna
- plasmids- carries DNA
-flagella for moving around locomotion ( moving from place to place)
- mesosomes- mitochondria for bacteria
-
what are viruses and what are they made up of ?
viruses are non- living- divide by infecting other cells
parasites- cannot reproduce by themselves
- made of dna and protein
DNA inside a protein coat with protein receptors
how do we study cells?
what must the solution of the solution be before it is homogenates ?
what are the different densities?
what is the supernatant?
what is the sediment?
centrifugation:
solution needs to be:
cold: prevent enzyme activity
pH buffer: prevent organelles denaturing
isotonic- prevent osmosis
- homogenise solution with a homogeniser to make homogenate to separate and release cells
- filter to get rid of cell debris or any complex cells
- centrifuge it to get organelles by spinning at different speeds to get different densities
densities:
- nucleus
- chloroplast and mitochondria
- endoplasmic reticulum and ribosomes
supernatant- liquid part onto
sediment - contains the organelle at the bottom
what are the different types of microscopes?
what is the formula?
what is magnification?
what is resolution?
what is the object ?
what is the image?
what is an graticule?
optical microscopes:
light wave is long, low resolution
vacuum cane be alive or dead
thin so light can pass through
low magnification
electron microscopes:
transmission (electrons pass through)
2d
high resolution
highest magnification
artefacts (artificial structure - ink )
dead vacuum
scanning ( electrons deflect)
3d
high resolution
dead vacuum
I
M R
magnification- how many times bigger the image is compared to its actual size
resolution- ability to distinguish between 2 points
object- material under lens
image- picture produced by lens
graticule is a little ruler that can be placed in the lens to measure parts of the specimen
what is mitosis for?
what are the different stages of mitosis?
what part is mitosis ?
what part is cytokinesis?
replicating cells for growth and development
interphase;
g1 cell gets bigger
s synthesis of dna
g2 organelles complete full set
prophase:
nuclear envelope disintegrates chromosomes condense and become visible when stained
centrioles move to either end of the cell
metaphase;
chromosomes line up to the middle of the cell
spindle fibres attach to centromeres
anaphase
spindle fibres contract and pull apart chromosomes
telophase
chromatids move to either end of cell and nuclear envelope forms
cytokinesis:
cytoplasm splits
mitosis- when nucleus divides
cytokinesis- cell divides into 2
how do viruses replicate?
what does the exiting of the virus produce?
-viruses attach to cell via protein receptor and release nucleic acid
-the host cell uses this nucleic acid to replicate viral particles
- the cell to burst and the viral particles release into the blood stream
or - budding happens where viral particle take of part with membrane
-the exiting of the viral particles damages the host cell causing disease
-viral particles result in the death of cells
how does prokaryotes replicate?
what bus happen in order of a bacterial cell to survive?
prokaryotes replicate by binary fission:
- replication of DNA and plasmids
- cytoplasm spilts cell into 2 daughter cells with a copy of DNA and a variable number of plasmids
side note
if a daughter cell does not have a single DNA or at least ONE copy of a plasmid they die
what is the build up of the body?
what are some specialised cells?
cells- tissues- organs- organ systems
specialised cells:
- sperm:
tail so it can swim
head which contains enzymes to digest egg cell membrane
packed with mitochondria for energy to swim
- palisade layer:
packed with chloroplast for photosynthesis
- transparent so light can get through
- at surface of light for maximum light energy
xylem:
- cells are dead to prevent water uptake
lined with lignin for strength for turgidity
- continuous hollow tube with no cells at the end
what is cancer?
what is cancer caused by?
which tumour is cancerous?
how quickly do these tumours grow?
what happens to most cells when they mutate?
what is chemo therapy?
what types of drugs are used?
why is hair loss common in chemotherapy ?
- growth disorder of cells ( uncontrolled mitosis)
- caused by mutation of DNA
- 2 types of tutors benign ( non cancerous) stays within a membrane and malignant ( cancerous) spreads around the body
- benign- slow malignant- quick
- mutations happen all the times, thee is either early cell death of the immune system takes action
- chemotherapy is using drugs to stop cancer
- p53, control the division of cells
- vincristine and taxol- prevent spindle fibres forming
- methotrexate- prevent replication of dna
- hair loss is common as these drugs disrupt cell cycle
TRANSPORT ACROSS CELL MEMBRANES:
what and why is the plasma membrane known as?
what is the plasma membrane made up of?
- fluid- components can move within membrane
- mosaic made up of lots of different parts
- model- scientific representation
phospholipid
cholesterol: increases fluidity- more cholesterol means less substances can move in and out
integral proteins:
take up the width of the membrane:
transport membranes
e.g carrier and channel proteins
periphery proteins:
attached onto integral proteins and can disassociate into cell membrane
act as signalling cells:
- receptors for hormones/ neurotransmitters
- endocytosis- engulfing bacteria
- joins cells together
what can pass through the phospholipid bilayer?
- lipid soluble molecules
- very small polar molecules
- non polar molecules
what are the different types of transport?
- diffusion
- facilitated diffusion
- co transport
- active transport
- osmosis
what is diffusion ?
what is the gradient?
what process is diffusion?
what factors effect diffusion ?
net movement of particles from a high concentration to a low concentration
passive process
down concentration gradient
temperature- diffusion is driven by kinetic energy, as temp increases and particles have more kinetic energy they can move faster increasing the rate of kinetic energy
- concentration gradient- larger gradient, quicker rate of diffusion
- thickness of membrane/ distance- thicker membranes decreases rate of diffusion as they have to travel further taking longer
- surface area- the greater the surface area the more particles which can diffuse increasing the rate of diffusion
what is facilitated diffusion?
what is the gradient?
what do channel proteins allow through?
what do carrier proteins allow through?
how do carrier proteins allow polar molecules through ?
polar molecules using channel and carrier proteins to pass into membrane from a high concentration to a low concentration
down concentration gradient
channel proteins allow water soluble molecules through
carrier proteins allow molecules such as glucose through
carrier proteins change shape letting the molecule enter or exit the cell
channel proteins open up and create a cannel to specific ions
what is osmosis?
what is the gradient?
what is the water potential?
what affects water potential?
what is the formula for water potential?
what is water potential measured in ?
what is the highest water potential ?
what values does water move from?
what process is osmosis?
what are the states of osmosis ?
water potential from a high concentration to a low concentration through a partially permeable membrane.
down concentration gradient
water potential- is the tendency for water to move
pressure potential- is the concentration of water
solute potential- if there are solutes water binds to it decreasing the concentration of water, decreasing the rate of osmosis
water potential= pressure potential+ solute potential
kilo pascals
the highest water potential is 0 which is pure water
water moves from a less negative to a more negative
- process is passive
- states are
isotonic same water potential inside and outside of cell
hypertonic water potential higher is cell so leave the cell
hypotonic- water potential higher outside the cell, so moves into the cell
what is active transport ?
what process is active transport?
what is the gradient ?
what is the different stage of active transport?
can active transport happen twice at the same time?
active transport is molecules moving from a low concentration to a high concentration using ATP and carrier proteins.
process is active as it uses ATP
against concentration gradient
- the molecule binds to carrier protein
- ATP binds to carrier protein
- hydrolysis of ATP to give ADP and an inorganic ion ( the energy )
- this creation causes carrier protein to change shape and release ion/ molecule
- the inorganic phosphate is released causing the carrier protein to change back to its original shape
- sodium- potassium pump:
sodium actively removed from cell while potassium actively taken in to cell
what is co transport ?
where is an example this takes place ?
what are the different stages ?
Is co transport direct or indirect ?
molecule moving from low concentration to a high concentration via another molecule.
in the villi to the epithelial cell
- sodium potassium pump: sodium is actively pumped out to create a concentration gradient so the sodium can diffuse into the epithelial cell form the villi
- as the sodium ions diffuse into the epithelial cell, the sodium brings a glucose or amino acid molecule with it.
- the glucose or amino acid is going against of its concentration gradient hence why it is active transport
it is an indirect form of active transport because it is the sodium ions which drive the glucose or amino acid against their concentration rather than the ATP
what is the mitotic index practical?
- get root tip - where meristem is which is where mitosis takes place- remove whole plant so other students don’t try to use plant as it doesn’t have the root tip on where mitosis takes place
- put in heated hydrochloric acid for 15 minutes- breaks down pectin which holds the cells together to get a single layer, so the chromosomes can be seen more clearly
heated acid so cells separate faster - put in excess distilled water to neutralise hydrochloric acid, in excess so root tip doesn’t dry out
- blot root tip with tissue so it doesn’t dilute the ink
- add stain to make chromosomes visible
- squash with slide to get single layer
- put under microscope
- mitotic index= number of cells dividing/ total number of cells x 100
what is the osmosis practical ?
get a borer and get 3 potatoes sticks and chop into 2cm3
remove skin of potatoes as it effects rate of osmosis
measure mass of potatoes stick
get 3 test tubes and add different concentrations of sucrose
put in water bath to reach temperature
add potato piece into each test tube and place back in water bath
blot with tissue to remove excess water
measure mass of potato
what is the plasma permeability practical?
get different pure concentrations of beetroot into 6 test tubes
get 6 test tubes with different concentrations of ethanol alcohol e.g 20,40,60,80 percent
put in water bath of 30 degrees
blot 6 discs of beetroots with tissue to remove excess water
place beetroot into each of test tubes and place back in water bath
shake every 5 mins
remove beetroot piece
compare to standardised colours of different concentrations of pure beetroot– subjective
so put solution into cubes and use colorimeter which shows how much light is absorbed
high colimeter value- more light absorbs- more permeable membrane
ethanol disrupts membrane causing pigment to come out so higher ethanol concentration, higher permeability
what is immunity ?
what are non specific defence mechanisms?
what are self antigens?
what are non self antigens?
how do lymphocytes recognise self antigens?
what is phagocytosis?
what are B lymphocytes?
what are T lymphocytes?
what T helper cells are formed
what is cell mediated immunity ?
what are cytotoxic cells ?
the body fighting off a pathogen
- skin, hair,sebum oil tears contain antibacterial enzymes, hydrochloric acid in stomach
- self antigens are produced in your own body e.g cancer cell
- non self antigens are antigens formed from outside of your body e.g bacteria
- some lymphocytes have receptors that fit body cells, so these lymphocytes are either suppressed or die
- phagocytosis is where the pathogen releases chemicals which attracts the phagocyte, phagocyte engulfs pathogen and places it in a vesicle with lysozyme enzymes which break down pathogen and release antigens onto cell surface membranes.
- b lymphocytes mature in the bone marrow
- T lymphocytes mature in the thymus gland
- cell mediated immunity is when T cell binds to receptor of presenting antigen on white blood cell, and a chemical is release forming a clone of T helper cells
- T helper cells include:
- cytotoxic cells
- develop memory cells
- stimulate B helper cells
- humoral immunity is where the T cell binds to antigen presenting white blood cell and a chemical is released forming plasma cells which produce antibodies which fin pathogen mark and disable it for phagocytosis and memory cells for future infection which turn into plasma cells.
- cytotoxic cells produce a protein called perforin which cause wholes in cell membrane letting pathogen be freely permeable, mostly on viruses as they reproduce in the cell
what are antibodies?
what do antibodies form ?
what are monoclonal antibodies?
what are monoclonal antibodies used for?
what are ethical uses of monoclonal antibodies ?
- polypeptide chain made up of one heavy chain and one light chain with a variable region
- form antigen- antibody complex
- proteins made in Laboratory that act as antibodies injected into humans
used for :
cancer cells, they attach onto receptor and block chemical which causes growth - pregnancy tests which contain monoclonal antibodies which attach to receptor of antigen released by placenta when pregnant causing colour change
- used for diagnosing illnesses
-ethical problems: - volunteers have suffered from organ failure
-tested on mice, have to insert mice with a tumour
-not always worked some people have died
what is passive immunity?
what is active immunity?
what is natural active immunity?
what is artificial passive immunity?
what is a vaccination?
what is a successful vaccination ?
why does a vaccination not eliminate a disease?
what are the ethics of using vaccines
introducing antibodies from an outside source into the body
where the body makes its own antibodies
pathogen that has entered the body naturally
antibodies have entered body from a vaccination
vaccination is a dead or inactive pathogen which stimulates an immune response
herd immunity is when the majority of people are vaccinated
- able to be stored and transported, cheap, available, able to help majority of people, few side effects, people to administer vaccine
- babies have not a fully functioning immune system , old people have a weak immune system, religious reasons, pathogen mutates frequently, certain pathogens hide in cells so antibody can’t find pathogen
- production usually involves animals, dangerous side effects, dangerous trials, unknown health risks in future
