Cell Biology Flashcards
2 types of eukaryotic cells
animal + plant
what do animal + plant cells both have in common
both have a nucleus
what does nucleus contain
DNA of the cell
3 key features of eukaryotic cells
eukaryotic cells have a cell membrane, cytoplasm and genetic material enclosed in a nucleus.
what are bacteria
prokaryotes
key difference of prokaryotic cells
genetic material not inclosed in a nucleus
what cells are smaller
prokaryotes/ eukaryotes
prokaryotes much smaller
6 features in a prokaryote
cell membrane
cell wall
cytoplasm
plasmids
loop of dna
flagellum
4 characteristics of prokaryote
single celled
x nucleus- loop of dna
plasmids- small dna rings
smaller then eukaryots
measurement names in descending order
metre
centimetre
millimetre
micrometre
nanometre
symbols for measurements in descending order
m
cm
mm
μm
nm
multiplication factor of measurements
(what would you times it by to get number in metre)
metre 1
centimetre 10^-2
millimetre 10 ^-3
micrometre 10 ^-6
nanometre 10^-9
example of something that’s 1mm
tip of ball point pen
size of typical human cell
10-20 μm
size of one heamaglobin molecule
5nm
what does 1 order of magnitude mean
10 times
a pineapple is 10 times larger than a lemon.
describe using order of magnitude
pineapple 1 order of magnitude larger than lemon
a dog is 100 times longer than a wood louse.
describe using order of magnitude
dog is 2 orders of magnitude longer than wood louse
every order of magnitude is … … greater than the one before
every order of magnitude is 10 x greater than the one before
how many orders of magnitude is 1000x
3 orders of magnitude
(count 0’s)
name 5 subcellular structures in animal cell
nucleus
cytoplasm
cell membrane
mitrochondria
ribosomes
how do you know that animal cells are eukaryotic
genetic material enclosed in nucleus
what is the cytoplasm + function
watery solution where chemical reactions take place
example of chemical reaction that can take place in cytoplasm
first stage of respiration
function of cell membrane
controls which molecules enter + leave cell
why can’t we see mitochondria and ribosomes on some pictures
they are too small
function of mitrochondria
site of aerobic respiration
provide energy for the cell
ribosomes are very small. Can they be seen with an electron microscope, a light microscope, or both
electron microscope
function of ribosomes
site of protein synthesis
example of what protiens are used for
enzymes
whats smaller, mitochondria or ribosomes
ribosomes
differences between plant and animal cell
plants have a regular shape
(animal cells can change their shape easily)
plant cells packed with chloroplasts
what does the nucleus contain
genetic material
what structures do plant and animal cells share
nucleus
cytoplasm
cell membrane
mitochondria
ribosomes
what additional structures do plant cells have
-function
chloroplasts- site of photosynthesis
cell wall- strengthens cell
permanent vacuole- gives plant cell shape
what do chloroplasts contain
chlorophyll
what is the cell wall made of
cellulose
what is the vacuole filled with
cell sap
most / some / few animal cells are specialised
choose an option
most
what does it mean if an animal cell is specialised
has adaptations to help carry out a particular function
what do scientists call it when cells become specialised
differentiation
job of sperm cell
join with an ovum
a sperm cell is present in the process of what
fertilisation
what is an ovum
egg cell
what happens during fertilisation
the genetic info of the ovum and the sperm cell combine
4 adaptations of sperm cells
-only contain half the genetic info of a normal adult cell
-long tail that is streamlined
-packed full of mitochondria
-contain enzymes
why do sperm cell have a long tail that is streamlined
streamlined makes swimming easier
tail to swim
why are sperm cell packed full of mitrochondria
to get energy for swimming
why do sperm cells contain enzymes
so they can digest through outer layer of ovum
job of nerve cell
send electrical impulses around body
adaptations of nerve cell
long axon
myelin sheath insulates axon
synapses at end of axon
cell body has dendrites
what does axon do
carries electrical impulses from one part of the body to another
what does the myelin insulating the axon do
speeds up transmission of nerve impulses
what are synapses
junctions that allow impulses to pass from one nerve cell to another
what do dendrites do
increase surface area so other nerve cells connect more easily
key feature of muscle cells
they contract
adaptations of muscles cells
contain protien fibres
packed with mitrochondria
how do protien fibres work in a muscle cell
when a muscle cell contracts, protien fibres shorten, decreasing length of the cell
why are protien fibres useful for muscle cell
they can change their length
why are muscle cell packed full of mitrochondria
provide energy for muscle contraction
what do muscle cells work together to form
muscle tissue
what are the 3 specialised animals cell u need to know
sperm cells
nerve cell
muscle cells
3 specialised plant cells u need to know
root hair
xylem
phloem
adaptations of root hair cell
root hairs
dont contain chloroplasts
why are the hairs helpful to the root hair cell
3 points
increase s.a
so root can absorb water and dissolved minerals easily
why do root hair cells not contain chloroplasts
because they are underground
(chloroplasts contain chlorophyll- they are the site of photosynthesis
photosynthesis requires light energy
the root cant get light energy
so no need for chloroplasts)
where are xylem cells found
in plant stem
what do xylem cell form
long tubes
what do xylem tubes carry-
from where to where
xylem carries water and dissolved minerals from roots to leaves
very thick walls -containing lignin
end walls between cells are broken down
no nucleus, ribosome, chloroplasts
(no internal structures)
thick cell walls in the xylem are sealed with lignin
positive and negative of this
provide support to plant
xylem cells die
why is it useful that in xylem cells, the end walls between cells are broken down
the cells can form a long tube- water and dissolved minerals can flow easily
xylem cells have no internal structures. why is this good
easier for water and minerals to flow
job of phloem tubes
carry dissolved sugars up and down plant
what two cells do phloem cells consist of
phloem vessel cell
companion cell
adaptations of phloem vessel cell
no nucleus-limited cytoplasm
end walls have pores-sieve plates
phloem vessel cells have:
no nucleus-limited cytoplasm
end walls have pores-sieve plates
why ?
allow dissolved sugar to move through interior of phloem vessel cell
adaptation of companion cell
companion cell has mitrochondria
why is it useful that the companion cell has mitochondria
mitochondria in companion cell provide energy to the phloem vessel cell.
why do phloem vessel cells not have many mitrochondria
because they have a limited cytoplasm
how is the companion cell and phloem vessel cell connected
by pores
stage
lamp
objective lenses
eyepiece
coarse focusing lens
fine focusing lens
what do we put on the stage of the microscope
the microscope slide
what does the stage have to keep the slide in place
clips
what is below the stage
the lamp
what happens to the light from the lamp
it passes through the microscope slide
what do some optical microscopes have instead of a lamp
a mirror
what does the mirror in an optical microscope do
reflect light up through the microscope slide
what is found above the stage
the objective lenses
how many objective lenses do most microscopes have
give examples of the magnification these can have
3
4x 10x 40x
what is found at the top of the microscope
eyepiece
what does the eyepiece contain
the eyepiece lens
what magnification does the eyepiece lens have
10x
name the two dials found on an optical microscope
coarse focusing dial
fine focusing dial
RP 1-use a light microscope to observe, draw and label a selection of plant and animal cells
place slide onto stage
use clips to hold slide in place
select lowest power objective lens
-position objective lens so it almost touches the slide
- to do this, slowly turn coarse focusing dial
-look at microscope from side while adjusting objective lens
-look down eyepiece and slowly turn CFD till cells come into focus
-use FFD to bring cells into clear focus
-use pencil to make clear, labelled drawing of some of the cells
- write down the magnification
what will happen if we look through the eyepiece while adjusting the objective lens
could damage the slide
what does turning the CFD cause
increases distance between objective lens and slide
how to calculate total magnification
mg of eyepiece x mg of objective lens
once we’ve worked out total magnification we can select a higher power objective lens eg 10x. what must we do when selecting a higher power objective lens
adjust fine focusing dial to bring cells back into focus
when using an optical microscope on an animal cell, what structures can be seen
cytoplasm
nucleus
cell membrane
mitrochondria
when using an optical microscope on an animal cell, what structures can be seen
cytoplasm
nucleus
cell wall
vacuole
chloroplasts
what should you include on your drawing
how would you do this
magnification scale
put clear ruler over stage
measure diameter of field of view in mm
show this on drawing using a scale bar
write magnification eg 100x
early microscopes and modern microscopes both use what to view a specemin
light
downsides of light microscope- technical aspects
limited magnification
limited resolution
what does limited resolution mean
even if we increase magnification, the image will be blurred
what does limited magnification mean
magnification isnt powerful enough
why was electron microscope created
to study cells in finer detail
key advantage of electron microscope
much higher resolution and magnification than light microscope
example of what an electron microscope can do, a light microscope cant
see detail in the nucleus
magnification= image size/actual size
what is the size measured in
mm
are bacteria prokaryotes or eukaryotes
pro
bacteria multiply by………..
simple cell division
another word for simple cell division is
binary fission
describe binary fission
one bacterial cell splits into two bacterial cells
how often can bacteria carry out binary fission
what does this depend on
once every 20 mins
enough nutrients
suitable temp
number of bacteria =
2^n
n is number of rounds of division
a type of bacterium divides every 20 minutes. calculate no. of bacteria present after 3 hours in standard form
3 hours = 180 mins
180 / 20 = 9 rounds of division
2^9 = 512
5.12 times 10^2
how to prepare an uncontaminated bacteria culture using aseptic techniques
4 things u must do
–Petri dishes and culture media sterilised before use
–inoculating loops sterilised by passing through a flame
– lid of the Petri dish secured with adhesive tape + stored upside down in incubator
– incubated at 25* in school laboratories
what is an agar gel plate
nutrient broth set into a gel
in a petri dish
what do bacteria do on an agar gel plate
grow into visible colonies
Petri dishes and culture media must be sterilised before use. why
to kill unwanted microorganisms
prevent contamination
an innoculating loop is used to…..
transfer bacteria into the culture
why is the lid of petri dish attached with tape
to stop lid from falling off
and unwanted microorganisms entering
why is the agar plate stored upside down in the incubator
stop moisture dripping down onto bacteria and disrupting colonies
in school laboratories, cultures should generally be incubated at
25°C. why
reduces chances that harmful bacteria will grow
RP 2: investigate the effect of antiseptics or antibiotics on bacterial growth
using agar plates and measuring zones of inhibition.
describe the 7 steps
-clean bench with disinfectant solution
- sterilise innoculating loop by passing through bunsen flame
-open sterile agar gel plate near bunsen burner flame
-spread chosen bacteria evenly over plate using loop
- place sterile filter paper disk containing antibiotic onto plate
- incubate plate at 25*
-after few days measure zone of inhibition using πr².
why do we clean the bench with disinfectant solution
kill microorganisms that could contaminate our culture
why do we open the agar gel plate near the bunsen burner flame
flame kills bacteria in the air
In RP2 (investigating effect of antibiotics on bacteria growth using agar gel plates) what did the bacteria do
formed a layer on the agar gel
what is the zone of inhibition and the equation
region where bacteria havent grown
πr².
calculation zone of inhibition helps us measure ……
the effect of the antibiotic
what is found in the nucleus
chromosomes made of dna molecules
how many of each chromosome is found in body cells.
are they single or paired
2 of each chromosome
paired
how many chromosomes do human body cells contain
23 pairs of chromosomes in human body cells
which human cells contain unpaired chromosomes
gametes
ow many chromosomes do gametes have
23 UN paired chromosomes
what do chromosomes carry a large number of?
(not dna)
genes
what do genes do
determine many of our features
how many genes do most human chromosomes contain ( approx)
hundreds
what is the cell cycle
the series of stages for cells to divide
2 ways cells can divide by
mitosis
meiosis
brief 3 main stages of the cell cycle,
1 to 2 words to describe each stage
-growth and replication
-mitosis.
-division
1st stage of cell cycle
4 points
cell grows
number of sub cellular structures increases
DNA replicates
2 copies of each chromosome formed
2nd stage of cell cycle
4 points
mitosis-
1 set of chromosomes pulled
to each end of cell
nucleus divides
3rd stage of cell cycle
3 points
cell membrane and cytoplasm divide to form 2 identical cells
how many cells and how many chromosome pairs are there at the start and at the end of the cell cycle
1 cell- 2 pairs of chromosomes
2 identical cells- 2 pairs of chromosomes
really simply, what does mitosis do
copies one cell intotwo
functions of mitosis
x3
growth and development of multicellular organisms
for an organism to repair itself
asexual reproduction
what does multicellular organism mean and example
organism with more than one cell
plants/animals
what happens to the ovum after its fertilised
4 points
-ovum undergoes mitosis
-forms an embryo
-the cells in the embryo undergo mitosis
-cells in embryo change into specialised cells
what is an embryo
ball of cells
define differentiation
the process of specialisation
what is special about the cells in an early embryo
3 points
they have not differentiated
they can differentiate into any type of body cell
what are embryonic stem cells
the undifferentiated cells in an early embryo
define stem cell
an undifferentiated cell
that can give rise to more cells
of the same type
and can differentiate
to form other types of cells
where can stem cells be found in adults
bone marrow
what can adult bone marrow stem cells differentiate into
blood cells
eg
wbc
rbc
platelets
unlike ….. stem cells …… stem cells can ….. differentiate into …. other type of cell
unlike embryonic stem cells, adult stem cells can not differentiate into any other type of cell
stem cells use in medicine
bone marrow transplant
therapeutic cloning
what is leukemia
cancer of the bone marrow
process for a patient with leukemia get a bone marrow transplant
5 points
-patients existing bone marrow destroyed using radiation
-recieve transplant of bone marrow from donor
-stem cells in bone marrow divide
-new bone marrow is formed
- stem cells in bone marrow also differentiate and form blood cells
2 problems with bone marrow transplants / stem cell transplants
donor must be compatible with patient
viruses can pass from donor to patient
why must the bone marrow donor be compatible with the patient
if not, white blood cells produced by the donated bone marrow could attack the patients body
What happens in therapeutic cloning - in the patients body and before
3 sentences
- an embryo is produced with same genes as the patient
-stem cells from the embryo transplanted into patient w/out being rejected by immune system
-stem cells differentiate inside patient to replace cells which don’t work correctly
what medical conditions can therapeutic cloning used to help
diabetes
paralysis
risks of therapeutic cloning
ethical/religious objections
transfer viral infection
what is special about meristem tissue
the tissue can differentiate into any type of plant cell
throughout entire life of plant.
where is meristem tissue found in plants
roots
buds
what can stem cells from meristems be used to produce
produce clones of a plant quickly + cheaply
what are the type of plant clones that can be produced from meristem tissue
why clone these plant type
rare species - to protect from extinction
crop plants with special features- large numbers for farmers
eg of a special feature crop plants may have
disease resistance
what are all cells surrounded by
a cell membrane
define diffusion
spreading out of particles of any substance resulting in the net movement of particles from an area of high concentration to lower concentration
the 3 substances that diffuse in and out of cell that u need to know
oxygen
carbon dioxide
urea
what do cells need oxygen for
respiration
what carries out respiration
mitrochondria
why are cells in blood surrounded by a high amount of o2
because oxygen is transported into bloodstream from the lungs
why does diffusion happen in cells in the blood
for mitochondria in a cell to carry out respiration, oxygen is needed.
there’s a higher amount of oxygen in the blood than in the cell
what is the oxygen brought into the cell for respiration, used to produce
energy
carbon dioxide
name a product that diffuses only out of cells in the body
urea ( a waste product)
where is the urea that diffuses out of cells created
in cells
when urea diffuses out of cells it diffuses into…..
blood plasma
once urea diffuses into the blood plasma, what is it excreted by
kidneys
2 substances that are transported in and out of cells in the body
carbon dioxide
oxygen
Factors which affect the rate of diffusion are:
difference in concentration
temp
s.a of the membrane
scientists call the difference in concentration ……..
concentration gradient
describe relationship between concentration gradient and diffusion
the greater the concentration gradient, the faster diffusion takes place
describe relationship between temperature and diffusion
the higher the temp. the greater the rate of diffusion
explain why the higher the temp. the greater the rate of diffusion
particles have mote kinetic energy
they move faster
describe relationship between s.a of cell membrane and rate of diffusion
the larger the s.a of cell membrane, the greater the rate of diffusion
describe simply the s.a to vol ratio of single-celled organisms
single- celled organisms have large s.a to vol ratios
(large surface areas compared to their volume)
what do single celled organisms rely on for transport of molecules in and out of cells
diffusion
give an example of a gas diffusing into a single-celled organism and include where the gas would diffuse through
oxygen diffuses in through membrane
work out s.a to vol ratio of a 1mmx1mm Cube
s.a = (1x1) x6 =6 mm^2
vol=1x1x1 =1 mm^3
s.a to vol = 6:1
describe relationship between increase in size of organism and s.a : vol ratio
as organisms get larger, s.a : vol ratio falls SHARPLY
As organisms get larger, s.a : vol ratio falls SHARPLY
what types of organisms is this a problem for?
describe how this is a problem for those organisms using the example of oxygen?
multicellular organisms
cells on surface can get enough oxygen by diffusion
cells in centre of organisms don’t get enough gas
they are too far away from surface
2 ways animals solved issue of diffusion not able to supply oxygen to cells in centre of organism
-special structures for gas exchange with high s.a
-transport system to carry gases around body
eg of special structure for gas exchange with high s.a in mammals
lungs
where do fish get their oxygen from
water
describe how fish get their oxygen
water passes into mouth
flows over gills
where the oxygens transported into bloodstream
what do gills contain that allow gas to pass in and out of blood
Many fine filaments
deoxygenated blood passes into filament
oxygen diffuses from water into blood
oxygenated blood returns to body
3 adaptations of filaments
give gills massive s.a
thin membrane
efficient blood supply
why do filaments in fish gills have a thin membrane
for a short diffusion pathway
2 things the efficient blood supply in filaments of fish gills do
takes the oxygenated blood away
ensures a high concentration gradient
filaments give gills massive s.a,
have thin membrane &
have an efficient blood supply.
what do these adaptations do
make diffusion as efficient as possible
the effectiveness of an exchange surface is increased by 4 things. what are they
large s.a
thin membrane
efficient blood supply
being ventilated (gas exchange)
define osmosis
the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane
describe a dilute and concentrated solution
dilute solution contains high water concentration
concentrated solution contains low water concentration
what do partially permeable membranes do
allow some, not all, molecules to pass through
describe the cytoplasm
a concentrated solution
what will happen to an cell when placed in water
osmosis will take place
(from outside to inside cell)
cell will expand
may burst
what will happen if animal cell placed in an extremely concentrated solution
water will move out of cell by osmosis
cell will shrink
what will happen if plant cell placed in water
water move into cell by osmosis
cell will expand
cell will become turgid
what does turgid mean
cell becomes swollen
what structure prevents plant cell from bursting when cell put in water
cell wall
what will happen if plant cell put in concentrated solution
water moves out of cell by osmosis
cell becomes flaccid
what does it mean if a cell becomes flaccid
the cell shrinks
RP3: investigate the effect of a range of concentrations of salt or sugar solutions on the mass of plant tissue
how would you carry out the practical
-peel potato skin
-use cork borer- make 3 potato cylinders
-trim cylinders to same length with scalpel - 3cm
-measure length and mass of each cylinder
-use ruler and balance
- put each into a test tube
- add 10cm^3 of different molar sugar solution to #1 and #2 tube
-add 10cm^3 distilled water to #3 tube
-leave cylinders overnight in rack so osmosis happens
- remove cylinders and roll on paper towel
- remeasure length and mass of cylinders
- calculate % change in length and mass
why do we use a cork borer when cutting potatoe
make all cylinders same diameter
why should we not cut potato pieces to less then 3cm long
wont be able to measure effect of osmosis
why use distilled water instead of tap water in RP3 with potatoes
distilled contains no dissolved substances
they could affect rate of osmosis
in RP3: investigate the effect of a range of concentrations of salt or sugar solutions on the mass of plant tissue
why do we roll potato cylinders on paper towel after leaving them in a solution over night
to remove surface moisture
potato has starting mass of 1.56g
this increases by 0.25g
how do u work out % increase
(0.25/1.56 ) x100
potato cylinder has starting mass of 1.32g
this decreases by 0.19 g
how do u calculate percentage decrease
(-0.19/1.32) x100
= -14.39% (to 2 dp)
in RP3: investigate the effect of a range of concentrations of salt or sugar solutions on the mass of plant tissue
what would the axis be on the graph you make
y= % change in mass
x= concentration of sugar/salt solution
in RP3: investigate the effect of a range of concentrations of salt or sugar solutions on the mass of plant tissue
describe the trend and reasons for the trend on your graph
negative gradient
( straight line )
goes from positive change in mass to negative
in water, potato gains mass through osmosis
in the concentrated solution, potato loses mass by osmosis out of cell
(in higher concentrated solution, potato loses even more mass by osmosis out of cells)
in RP3: investigate the effect of a range of concentrations of salt or sugar solutions on the mass of plant tissue
what does it mean when the line on your graph for change in mass against concentration crosses the x axis
no change in mass
concentration of sugar out of cell is same as concentration in cell
no osmosis happens
that value is the approx sugar concentration in the cell
what two graphs can be plotted from RP3: investigate the effect of a range of concentrations of salt or sugar solutions on the mass of plant tissue
change in mass against concentration of solution
change in length against concentration of solution
give two examples of the different molar sugar solutions that can be used in RP3
0.5 molar
0.25 molar
define active transport
movement of particles from an area of low concentration to an area of high concentration (dilute-concentrated solution) against the concentration gradient.
what does active transport require
energy from respiration
state the 2 differences between active transport and diffusion
AT:
movement against concentration gradient
requires energy
2 examples of active transport
include the molecule and where the molecule is travelling to and from
sugar absorbed from low concentrations in the lumen to cells by active transport then from cells to blood
mineral ions absorbed into root hairs from dilute solutions in soil
what is the lumen
what happens in the lumen
the cavity of the small intestine
where food is digested
what is found in the lumen
give an example
the molecules produced from digestion of food
(eg glucose)
what do mitochondria do
x2
carry out respiration
provide energy for active transport
why do plants need mineral ions
for healthy growth
what do root hair cells do
transport ions into plant from soil
give an example of a mineral ion a plant needs and what its used for
magnesium
to make chlorophyll in the leaves
what happens to mineral ions once they are absorbed by active transport from soil to root hair cells
ions transported to xylem vessel
and moved to the leaf
root hair cells contain many ……… to provide ……. for active ……..
root hair cells contain many mitochondria to provide energy for active transport
what are sugar molecules in our bodies cells used for
cellular respiration
