biology topic 1 - cell biology Flashcards
all living things are made of what?
cells
cells can be either what or what?
prokaryotic or eukaryotic
what are eukaryote cells?
they are complex and include all animal and plant cells
what are prokaryote cells?
they are smaller and simpler than eukaryotes
eukaryotic organisms are made up of what?
eukaryote cells
prokaryote is what?
a prokaryotic cell
what does the nucleus do?
contains genetic material that controls the activities of the cell
what does mitochondria do?
where most reactions for aerobic respiration happen
what does cytoplasm do?
its a gel like substance where most chemical reactions take place. it contains enzymes
what does the cell membrane do?
holds the cell together and controls what goes in and out
what do ribosomes do?
where proteins are made in the cell
what does a cell wall do?
it supports and strengthens the cell
whats the cell wall made of?
cellulose
what do chloroplasts do?
its where photosynthesis happens and where food is made for the plant
what do chloroplasts contain?
chlorophyll
what does chlorophyll absorb?
light needed for photsynthesis
what does the vacuole contain?
cell sap
if asked to work out the area of a subcellular structure what do you do?
work out the area of the shape its close to (rectangle)
what is bacteria?
prokaryote
what do bacterial cells have instead of a nucleus?
single circular strand of DNA that floats freely in the cytoplasm
in a bacterial cell, what are the single rings of DNA called?
plasmids
what don’t bacterial cells have?
chloroplasts or mitochondria
does the cell wall go on the outside or the inside of the cell membrane?
outside
what do microscopes let us see?
things we cant see with the naked eye
what do light microscopes use?
light and lenses
what do light microscopes let us see?
individual cells or large subcellular structures, like nuclei
what do electron microscopes use?
electrons
what do electron microscopes do better than light microscopes?
magnify an object and higher resolution
what can we see with electron microscopes ?
let us see smaller things in more detail( internal structures)
how do you calculate magnification?
image size/real size
how do you get from micrometres to mm?
divide by 1000
what do you do when calculating magnification if the number is very big or small?
put it in standard form
what is a slide?
a strip of clear glass
how do you prepare a slide?
put a drop of water on it
how do you prepare your onion to go onto the slide?
use tweezers to peel of the epidermal tissue from the onion skin
what do you add to the onion and water?
iodine so you can see the cell
what do you place on all water, onion skin, iodine?
a cover slip
whats the piece on a microscope you look into?
eyepiece
where do you put your slide on the microscope?
the stage
where is the light on a light microscope?
beneath the stage
what should your drawing be like of your magnified onion slide?
should take up at least half the space, no broken lines and should be drawn in proportion
what is differentiation?
the process by which a cell changes to become specialised for its job
cells that go through differentiation for mature animals are normally for what?
repairing or replacing cells
what is the function of a sperm?
to get the male DNA to the female DNA
how is it adapted to its function?
it has a long tail and a streamlined head to help it swim to the egg
what do sperm cells have a lot of?
mitochondria to give it the energy needed
what do sperm carry in its head to digest through the egg cell membrane?
enzymes
what is the function of a nerve cell?
to carry electrical impulses
how are nerve cells adapted to their function?
they are long with branched connection at their ends to connect to other nerve cells and form a network
what is the function of a muscle cell?
to contract quickly
how are muscle cells adapted to their function?
they are long and contain lots of mitochondria for contraction
what do root hair cells do?
absorb water and minerals
where do root hair cells grow?
on the surface of the plant roots
what does it give the plant with lots of root hair cells?
a large surface area for absorbing water and mineral ions from the soil
what are phloem and xylem cells specialised for?
transporting substances
what do phloem and xylem cells form?
phloem and xylem tubes which transport food and water around the plant
how are phloem and xylem tubes formed?
they are long and are joined end to end
what are the centre of xylem cells like?
hollow
what are the centre of phloem cells like?
very few subcellular structures so that stuff can flow through them
what are undifferentiated cells called?
stem cells
depending on what instructions they’re given what can stem cells do?
they can differentiate into different types of cells
where are stem cells found in humans?
human embryos
why do stem cells excite scientists and doctors?
because they have the potential to turn into any cell at all
where are stem cells found in adults?
bone marrow
unlike embryonic stem cells what can adult stem cells only do?
turn into certain cell types, like blood
what can stem cells be used to grow in a lab?
clones
what does lots of medicine use to cure disease?
adult stem cells
what can stem cells from a healthy person do if transferred to a patient?
replace faulty blood cells
what can embryonic stem cells be used for?
to replace faulty cells in sick people
fro people with diabetes what could embryonic stem cells make?
insulin-producing cells
what can embryonic stem cells produce for a paralysed or spinal injury patient?
nerve cells
what can therapeutic cloning be used for?
to make stem cells with the same genetic makeup as the patient therefore the patients body wouldn’t reject the cells
what are the risks of using stem cells in medicine?
stem cells grown in the lab may become contaminated with a virus which could make the patient sicker
why are some people against stem cell research?
because they believe that human embryos shouldn’t be used for experiments as they are a potential human life
stem cell research is very controversial to the point where it is banned in some countries how is it allowed in the UK?
as long as it follows strict guidelines
where are stem cells found in plants?
the meristems
what can meristem stem cells produce?
clones of a whole plant quickly and cheaply
what can meristem cells also be used for ?
grow plants of rare species
what can meristem cells be used for regarding desired characteristics ?
they can grow crops of identical plants but with desired features eg disease resistant
what do cells in our body contain our genetic material in the form of ?
chromosomes
what do chromosomes contain?
genes that control the development of different characteristics
what do body cells normally have?
two copies of each chromosome - one from the father and one from the mother
how many pairs of chromosomes are their in a human cell?
23
when body cells in multicellular organisms divide to produce new cells whats it part of ?
the cell cycle
the stage of the cell cycle where the cell divides is called what?
mitosis
what do multicellular organisms use mitosis for?
to grow or replace cells that have been damaged
what does the end of the cell cycle result in?
in two new identical daughter cells
in a cell that’s not dividing how is the DNA spread out?
in long strings
before a cell divides it has to grown and increase the mount of what?
subcellular structures
what happens in cell division after the subcellular structures duplicate?
the DNA duplicates ands forms X shaped chromosomes with identical arms
what happens in mitosis?
the chromosomes line up In the middle of the cell then cell fibres split them up. they move to the opposite ends and membranes form around the new chromosomes
what divides last in mitosis?
the cytoplasm and cell membrane
what is the product of mitosis?
two daughter cells with identical DNA to the parent cells
how do prokaryotes divide ?
binary fission
what happens in binary fission?
the circular DNA and plasmids replicate, the cell gets bigger and the DNA strands move to the opposite poles of the cell
what divides last in binary fission?
the cytoplasm divides and new cell walls form
what happens in binary fission after the cytoplasm divides?
two daughter cells are created
what are the daughter cells like in binary fission?
each daughter cell has one copy of the circular DNA but can have a varied number of plasmids
how often can bacteria replicate in the right conditions?
every 20 minutes
what happens to bacteria when they are In unfavourable conditions?
they stop dividing and die
how do you calculate the number of bacteria in a population?
total time bacteria is producing cells/ mean division time = number of divisions. then 2 to the power of number of divisions
what are bacteria grown on?
a culture medium
give an example of a culture medium?
agar jelly
how do you prepare an agar plate?
pour hot agar jelly into a petri dish and let the jelly cool/set
what is used to transfer microorganisms to the culture medium?
inoculating loop
what temperature shall cultures of microorganisms be kept at in school?
25 degrees
the temperature cultures of microorganisms are kept at in school is specific why?
if they are kept at over 25 degrees there is potential for pathogens to grow
in industrial conditions they are kept at a lot higher temperatures why?
so the culture will grow a lot faster
why does everything need to be sterilised when growing bacteria?
contamination of unwanted microorganisms will affect your results
what two things must be sterile before use?
the Petri dish and culture medium
how is the inoculating loop sterilised?
its passed over a burning flame
how is the lid of the petri dish put on after transferring the bacteria and why?
its lightly taped on to stop air microorganisms getting in
why are the petri dishes stored upside down?
to stop condensation falling onto the agar surface
when testing if antibiotics affect bacteria growth how do you do it?
place paper discs that are soaked in the antibiotic evenly spaced out and leaving space between them
what will the antibiotic do with the agar jelly?
diffuse ( soak into it)
what happens to antibiotic resistant bacteria?
it will continue to grow on the agar around the paper discs
what happens to antibiotic non resistant bacteria?
it will die
what’s the clear area around the disc where the bacteria has died called?
the inhibition zone
what control variable is used and has to be used in this experiment?
a paper disc soaked in sterile water
why do you need a control disc?
to see the difference of what the antibiotic does
how long do you leave the plate with the antibiotic on for?
48 hours
the more effective the antibiotic is against the bacteria, the larger the what?
inhibition zone
how do you compare sizes of inhibition zones?
calculate the area of the inhibition zones
how do you find the area of the colony?
measure the diameter of the colony you want to find first
what is diffusion?
the spreading out of particles from an area of higher concentration to an area of lower concentration
what does diffusion happen in?
solutions and gases
what is a concentration gradient ?
the difference in concentration
the bigger the concentration gradient the what?
the faster the diffusion rate
how does a higher temperature give a faster diffusion rate?
the particles have more energy therefore they move around faster
only what can diffuse through cell membranes?
only very small molecules
what small molecules can diffuse through cell membranes?
oxygen, amino acids, glucose and water
what is osmosis?
the movement of water particles across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration
what is a partially permeable membrane?
a membrane with very small holes in it so that only small molecules can pass through it
because there is more water molecules one side there is what?
a steady net flow of water into the region with fewer water molecules
how can you test osmosis?
cut identical cylinders of potato and put them in water and sugar solutions of high concentration
what do you measure first before putting the cylinders in the solution?
the mass of the potato cylinders
how long do you leave the potato in the solution?
for 24 hours or so
when you take the potato out what do you do?
dry the potato gently and measure the mass again
if water has been drawn in by osmosis, what will happen?
the mass will increase
if water has been drawn out by osmosis what will happen?
the mass will decrease
what is the dependant variable of this experiment?
chip mass
what is the independent variable of this experiment?
concentration of sugar solution
what happens in active transport?
when substances are absorbed from a lower to higher concentration ( goes against the concentration gradient)
how do root hairs take in minerals?
via active transport
what does active transport allow the plant to do?
absorb minerals from a dilute solution against the concentration gradient
what does active transport need that diffusion and osmosis dosent ?
needs energy from respiration
where does active transport happen in human?
taking glucose from the gut
what is active transport used in the gut for?
when there is a lower concentration of nutrients in the gut than there is blood
what normally happens in the gut and why?
diffusion as when theres a higher concentration of nutrients they naturally diffuse into the blood
therefore what does active transport allow ?
nutrients to be taken into the blood despite the fact that the concentration gradient is the wrong way
how easy it is for an organism to exchange substances with its environment depends on what ?
the organisms surface area to volume ratio
the larger the organism the what?
the smaller its surface area to volume ratio
how do you work out surface area to volume ratio?
work out the surface are of the object and then its volume
what does it tell us if the surface area to volume ratio of a mouse is 6:1?
it has a surface area 6 times its volume
why do dingle celled organisms only need direct diffusion?
because they have a large surface area compared to volume therefore its easy to exchange substances across the membrane
why do multicellular organisms need exchange surfaces?
because they have a smaller surface area compared to their volume - not enough substances can diffuse from the outside to supply their entire volume
how are exchange surfaces adapted regarding membranes?
they have a thin membrane, so there is a short diffusion distance
how are exchange surfaces adapted regarding surface area?
they have a large surface area so lots of substances can diffuse at once
how are exchange surfaces adapted regarding blood?
exchange surfaces in animals have lots of blood vessels to get stuff in and out of the blood quickly
how are exchange surfaces adapted regarding gas?
they are well ventilated so air can easily diffuse out
how does gas exchange happen in the lungs?
it diffuses oxygen into the blood and diffuses out the waste carbon dioxide
where does gas exchange happen in the lungs?
alveoli
how are alveoli adapted to gas exchange?
they have a large surface area, a moist lining, very thin walls and a good blood supply
in the small intestine what provides a really large surface area?
little projections called villi
why does the small intestine need a large surface area?
so that food is absorbed much more quickly into the blood
how is a leaf adapted to exchange surface regarding the underneath of the leaf?
it has little holes called stomata where the co2 diffuses in through
how is a leaf adapted to exchange surface regarding oxygen and water vapour?
they diffuse out through the stomata
how is a leaf adapted to exchange surface regarding the flattened shape of the leaf?
it increases the surface area of the exchange surface area
how is a leaf adapted to exchange surface regarding the air spaces in the leaf?
this also increases the surface area
what do gills have to be good at gas exchange?
a large surface area
what enters the gills via diffusion?
water containing oxygen which then diffuses from the water and oxygen foes into thr blood
what gives the gills a large surface area ?
thin plates called gill filaments
what do gill filaments have on them that increases the surface area even more?
lamellae (little tiny structures)
what does the lamellae have to speed up diffusion?
lots of blood capillaries
what maintains a large concentration gradient between the water and the blood ?
blood flows through the lamellae in one direction and water flows through the opposite direction
how does lots of diffusion happen from thw water into the blood?
because theres lots of oxygen in the water compared to the blood
