cell biology Flashcards
prokaryote
a prokaryotic cell (without nucleus)
a single-celled organism - unicellular
another word for prokaryote + example
unicellular organism i.e bacterium
eukaryote
organisms made up of eukaryotic cells with genetic material enclosed in the nucleus
5 subcellular structures in animal cells and what they do
nucleus - contains genetic material/ controls activity of cell
cytoplasm - a gel-like substance containing
enzymes where chemical reactions take place
cell membrane - holds cell together and controls what goes in and out
mitochondria - the energy source of the cell where most chemical reactions take place
ribosomes - where protein synthesis takes place
3 subcellular structures only in plant cells and what they do
- cell wall - made of cellulose supports and strengthens cell
- permanent vacuole - contains cell sap
- chloroplasts - contains a green pigment called chlorophyll that absorbs light needed for photosynthesis
what subcellular structures do bacterium contain and what do they do
cell wall - made of cellulose supports and strengthens cell
cytoplasm - a gel-like substance containing
enzymes where chemical reactions take place
cell membrane - holds cell together and controls what goes in and out
singular strand of DNA that floats freely around the cytoplasm
one or more small rings of DNA called plasmids - give antibacterial resistance
plasmids
one or more small rings of DNA that give antibacterial resistance found in bacteria cells
cell membrane
cell membrane - holds cell together and controls what goes in and out found in all cells
cytoplasm
cytoplasm - a gel-like substance containing
enzymes where chemical reactions take place found in all cells
cell wall
cell wall - made of cellulose supports and strengthens cell , found in bacteria and plant cells
chloroplast
chloroplasts - contains a green pigment called chlorophyll that absorbs light needed for photosynthesis found in plant cells
permanent vacuole
- permanent vacuole - contains cell sap
nucleus
nucleus - contains genetic material/ controls activity of cell
cytoplasm
cytoplasm - a gel-like substance containing
enzymes where chemical reactions take place
mitochondria
mitochondria - the energy source of the cell where most chemical reactions take place
4 differences between prokaryotes and eukaryotes
prokaryotes
- smaller in comparison
- cell division via binary fission
- always unicellular
- genetic material in single dna loop and plasmids
eukaryotes
- larger in comparison
- cell division via mitosis or meiosis
- often multicellular but sometimes unicellular
- genetic material enclosed in nucleus and no plasmids
equipment for microscopy practical (hint-9)
- small piece of onion or otherwise specified organism
- knife or scalpel
- a white tile
- forceps
- a microscope slide
- a coverslip
- a microscope
- iodine
- pippette
how many pieces of equipment are needed for the microscopy practical
9
microscopy practical preparation stage/ set up: (steps 1-6/7)
- 1 put one drop of water on the microscope slide using the pippette
- 2 separate a layer of the onion
- 3 peel a thin layer of epidermal tissue from the surface
- 4 use forceps to put it on the drop of water on the microscope slide
- 5 ensure the layer of onion cells is flat on the slide
- 6 put to drops of iodine on
- 7 carefully lower the coverslip onto the slide
microscopy practical method (steps 9-15)
- 9/1 select the lower power objective lense
- 10/2 move the stage as close to the objective as possible
- 11/3 place the prepared slide on the stage
- 12/4 focus away from the slide, using the coarse adjustment , until the specimen is in focus
- 13/5 move the high power objective in line with the slide
- 14/6 use the fine focusing adjustment to bring the specimen back into focus
- 15/7if the specimen cannot be brought back into focus, refocus under low power and repeat stages 5-6
2 risks of microscopy practical
- iodine could cause skin irritation
- iodine could cause eye irritation
what could be done to avoid skin irritation (microscopy rp)
- avoid contact with skin or wear gloves
- wash hands after handling bottle or slide
what could be done to avoid eye irritation (microscopy rp)
- wear safety goggles
microscopy practical steps - how would you put the coverslip on the slide
(carefully lower the coverslip onto the slide)
- place one edge of the coverslip on the slide
- then use a mounted needle to lower the other edge onto the slide
how do you go from a cm to a mm
x10
how do you go from mm to cm
divide by 10
how do you go from mm to um
x 1000
um to mm
divide by 1000
how do you go from um to nm
x 1000
how do you go from nm to um
divide by 1000
when do animal cells differentiate
in early stages of development
when do plant cells differentiate
throughout their life cycle
function of sperm cells
to fertilise egg cells for reproduction
3 adaptations of sperm cells
- Streamlined with a long tail to swim to the egg.
- Acrosome in the head containing enzymes to
digest the egg cell membrane. - Large number of mitochondria to release energy for movement.
3 adaptations of nerve cells
- Long to carry signals long distances.
- Branched connections to connect to other nerve
cells and form a network around the body. - Insulating sheath to enhance transmission of
electrical signals.
2 adaptations of muscle cells
- Contain a large number of mitochondria to
release energy from respiration for movement. - Long so that there is enough space to contract.
function of nerve cells
to carry electrical signals around the body
function of muscle cells
to contract for movement
2 adaptation of root hair cells
- Hair like projections to increase the surface area.
- no chloroplasts this is because they do not need them as they are in the soil
function of root hair cells
to absorb water and minerals from the soil
function of xylem cells
to carry water and minerals inside of plants
function of phloem
to carry glucose around the plant
3 adaptations of xylem cells
- Form hollow xylem tubes made of dead tissue.
- Long cells with walls toughened by lignin.
- Water and minerals flow from the roots towards the leaves only in one direction in a process called
TRANSPIRATION
3 adaptations of phloem cells
- Form phloem tubes made of living tissue.
- Cells have end plates with holes in them.
- Glucose in solution moves from the leaves to growth and storage tissues in a process called
TRANSLOCATION - two way movement
how do cells become specialised
As a cell differentiates it acquires different sub-cellular
structures to enable it to carry out a certain function. It has become a
specialised cell.
what is the main reason for cell division in mature animals
In mature animals, cell division is mainly restricted to repair and replacement.
how has the development of electron microscopes helped biologists to understand more subcellular structures
- An electron microscope has much higher magnification and resolving power than a light microscope.
- This means that it can be used tostudy cells in much finer detail.
- This has enabled biologists to see and
understand many more sub-cellular structure
magnification formula
size of image
——————–
size of real object
what specific genetic material is in the nucleus
The nucleus of a cell contains chromosomes made of DNA molecules. Each chromosome carries a large number of genes
how are chromosomes usually found in body cells
In body cells the chromosomes are normally found in pairs
what happens during the cell cycle
During the cell cycle the genetic material is doubled and then divided
into two identical cells.
what has to happen before a cell can divide
Before a cell can divide it needs to grow and increase the number of
sub-cellular structures such as ribosomes and mitochondria. The DNA
replicates to form two copies of each chromosome.
this is the growth stage of mitosis
what happens during mitosis stage of cell division
In mitosis one set of chromosomes is pulled to each end of the cell and the nucleus divides
and then Finally the cytoplasm and cell membranes divide to form two identical
cells.
why is mitosis important
Cell division by mitosis is important in the growth and development of
multicellular organisms
6/5 features of a light microscope
- uses light rays
- small and portable
- relatively inexpensive
- can see colour images
- lower resolution and magnification
5 features of an electron microscope
- uses electron beams
- large and nonportable
- expensive
- black and white images
- greater resolution and magnification
comparison between light and electron microscope
LIGHT
- uses light rays
- small
- relatively inexpensive
- can see colour images
- lower resolution and magnification
ELECTRON
- uses electron beams
- large and nonportable
- expensive
- black and white images
- greater resolution and magnification
what happens in the mitosis stage of mitosis
Finally the cytoplasm and cell membranes divide to form two identical
cells
what are the 3 stages of mitosis
growth
dna synthesis
mitosis
what are stem cells
Stem cells are undifferentiated cells within an organism. They can produce
other stem cells that can then differentiate into many different types of cells.
what are stem cells used for
Human stem cells can be used to help treat diseases
like diabetes and paralysis
what can human embryo stem cells differentiate to
Stem cells from human embryos can be cloned and made to
differentiate into most different types of human cells.
what can bone marrow stem cells differentiate to
Stem cells from adult bone marrow can form many types of cells
including blood cells.
what can meristem tissue in plants do and what can they be used for
Meristem tissue in plants can differentiate into any type of plant cell, throughout the life of the plant.
Stem cells from meristems in plants can be used to produce clones of plants quickly and economically.
where are stem cells in plants
meristem tissue
what happens during therapeutic cloning
In therapeutic cloning an embryo is produced with the same genes as
the patient. Stem cells from the embryo are not rejected by the patient’s
body so they may be used for medical treatment.
uses for meristem tissue in plants
Stem cells from meristems in plants can be used to produce clones of
plants quickly and economically.
* Rare species can be cloned to protect from extinction.
* Crop plants with special features such as disease resistance can be
cloned to produce large numbers of identical plants for farmers.
pros of embryotic stem cells
- can treat a wide variety of diseases/ problems
- plentiful
- painless
- using them is better than wasting them***
cons of embryotic stem cells
- possible harm / death to the embryo
- relatively untested , may not work
- arguably imoral , ethical issues - embryo cannot give consent, rights of embryos
pros for bone marrow stem cells
- no ethical issues/ permission given
- quick recovery
- well tested
cons for bone marrow stem cells
- operational hazards i.e infection
- fewer types of cells produced meaning fewer diseases/ problems it can treat
- painful
how do substances move into and out of cells
Substances may move into and out of cells across the cell membranes
via diffusion
3 types of diffusion in the body
diffusion, active transport and osmosis
diffusion
Diffusion is the spreading out of the particles of any substance in
solution, or particles of a gas, moving from an area
of higher concentration to an area of lower concentration.
examples of substances diffused within the body
- oxygen and carbon dioxide in gas exchange
- the waste product urea from cells into the blood plasma for excretion in the kidney.
factors affecting the rate of diffusion
Factors which affect the rate of diffusion are:
* the difference in concentrations (concentration gradient)
* the temperature
* the surface area of the membrane.
what does having a large surface area to volume ratio do for single celled organisms
This allows sufficient transport of molecules into and out of the cell to meet the needs of the organism.
3 areas where diffusion takes place in the human body
- small intestine
- lungs
- kidneys
3 examples of diffusion in the body
- digestion (from small intestines to capillaries
- gas exchange (from alveolar air space to blood around the lungs)
- urea (from cells to blood plasma)
what diffuses from small intestine and where
- digested foods (i.e amino acids / glucose)
- from small intestine
- to blood in capillaries of villus
what diffuses from lungs and where
- oxygen
- from alveolar airspace
- to blood circulating around the lungs
what diffuses to kidneys and where
- urea
- from cells
- from blood plasma
how does temperature affect the rate of diffusion
As the temperature increases the particles
in a gas or liquid gain more energy
so they move faster. The hotter it is the
faster the rate of diffusion
how does concentration affect rate of diffusion
A difference in concentration between
two areas next to each other. Particles
will move down the concentration
gradient from high to low.
how do you calculate surface area to volume ratio
divide surface area by volume
how do you calculate the volume
length x height x width
how do you calculate surface area
height x width
adaptations of the small intestine for diffusion
- Internal surface is covered in millions of
folds called villi. Villi increase the surface area. - Villi have a very good blood supply. This
maintains the concentration gradient. - Membranes of the villi are very thin to
allow for a short diffusion distance.
adaptations of lungs for diffusion
- Lungs contain millions of tiny air sacs
called alveoli.Alveoli increase the surface area. - Alveoli have a very good blood supply.
This maintains the concentration
gradient. - Membranes of the alveoli are very thin
to allow for a short diffusion distance. - well ventilated
adaptations in fish gills for diffusion*
- Each gill is made of lots of thin plates called
gill filaments, water with low oxygen flows over
them (however, the oxygen in the blood surrounding the gills is lower) . - Gill filaments increase the surface area.
- Gill filaments are covered with lamella
that increase the surface area more. - Lamella have a very good blood supply.
This maintains the concentration gradient as
water flows in the opposite direction. - Membranes of the lamellae are very thin
to allow for a short diffusion distance.
Examples of diffusion in fish
what are gill filaments and what do they do
Each gill is made of lots of thin plates called
gill filaments, water with low oxygen flows over
them (however, the oxygen in the blood surrounding the gills is lower)
adaptations in root hair cells for diffusion
- The root surface is covered in millions of
root hair cells. Root hair cells increase the surface area. - they are present on the mature parts of the roots.
- Absorb water and minerals from the soil
leaf adaptations for diffusion
- Large surface area to absorb more light.
- Thin so short distance for carbon dioxide
to diffuse into leaf cells. - Chlorophyll absorbs sunlight for
photosynthesis. - Xylem and phloem to support the leaf
and transport water and glucose. - Stomata on the lower side of the leaf to
allow gases to diffuse into and out of the
leaf
osmosis
Osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.
what affects the rate of osmosis
The rate of osmosis changes depending
on the concentration gradient and
temperature.
what does hypERtonic mean
more concentrated
solution than in the cells.(osmosis)
what does hypOtonic mean
more dilute than the
solution in the cells.(osmosis)
what does isotonic mean
same concentration as
the solution in the cell.
what is active transport
Active transport moves substances from a more dilute solution to a more
concentrated solution (against a concentration gradient). This requires
energy from respiration.
what does active transport require
energy from respiration
how is active transport used in plants and why do they need it
Active transport allows mineral ions to be absorbed into plant root hairs
from very dilute solutions in the soil. Plants require ions for healthy growth.
why do plants need active transport
Active transport allows mineral ions to be absorbed into plant root hairs Plants require ions for healthy
growth.
what is active transport used for in animals
It also 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.
why is active transport needed in animals
It also allows sugar molecules to be absorbed from the gut into the blood which has a higher sugar concentration. Sugar molecules are used for cell respiration.
aim of microbiology rp
to investigate the effects of antiseptics or antibiotics on bacterial growth using agar plates and measuring zones of inhibition
why is the aseptic technique used during the microbiology rp
to avoid contamination from surroundings to experiment which could ruin the results and from the experiment to the surroundings which could he a health hazard
equipment fro microbiology rp 9/7
- a nutrient agar plate
- a bunsen burner
- pipette
- culture of bacteria
- glass spreader ???
- filter paper discs
- 3 antiseptics
- beaker of ethanol
- discard beaker of disinfectant
- forceps
- tape
microbiology rp set up (steps 1- 3/4)
- 1 Spray the bench you are working on with disinfectant then wipe dry with paper towels.
-
2 On the bottom of the agar plate (not the lid) mark with a wax pencil / permanent marker:
a. 3 segments
b. a dot in the middle of each segment - “3” Wash your hands with antibacterial handwash.
- 4 Place the different antiseptics onto different filter paper discs.
microbiology rp method (steps 5-8)
- Lift the lid of the agar plate at an angle carefully and use forceps to place each filter paper
disc onto the dots. (Note down the antiseptic applied to each zone.) - Tape the lid onto the agar plate securely, but loosely enough that oxygen can still reach the
bacteria. - Place the agar plate in the incubator at 25 degrees celsius for 48 hours.
- Measure the diameter of the clear zones after 48 hours using a ruler. Do not remove the lid when taking measurements. and calculate the area
what must you do to the inoculating loop in the aseptic method
Sterilise the inoculating loop, by heating it in the Bunsen burner flame.
why must you sterilise the inoculating loop in the aseptic method
kills any bacteria that are present on the loop.
how should you put the lid back on in the aseptic method
place the lid as soon as possible, secure with tape. Label and invert the plate, and store upside down.
why must the lid be placed on quickly and stored upside down in the aseptic method
this stops additional unwanted bacteria in the air contaminating the plate
why must the bacteria be incubated at max 25 degrees in schools
this reduces the chance of growing harmful pathogens. Hospital laboratories would incubate plates at 37°C (body temperature) to allow quick growth and identification.
what safety precautions should you take during microbiology rp
Wear safety goggles when handling disinfectant.
Make sure to wash your hands beforeand after handling the bacteria.
why might a student get irregular results in microbiology rp (error)
- Shape of the clear zone may be irregular and the width is difficult to determine.
- Contamination from other bacteria may have occurred.
osmosis practical equipment(
- Plant tissue eg. potato
- A cork borer
- A measuring cylinder
- Boiling tubes
- Paper towels
- A sharp knife
- A white tile
- A range of salt or sugar solutions
- Distilled water
osmosis rp set up (steps 1-5)
- Use a cork borer to cut 5 potato cylinders.
- Trim the cylinders using a sharp knife and a ruler to the same length (about 3 cm).
- Accurately measure and record the length and mass of each cylinder.
- Measure 10 cm3 of the 1.0M sugar solution and transfer to the first boiling tube and label.
- Repeat step 4 for other concentrations of the solution and distilled water.
osmosis rp method (steps 5-4)
- Add one potato cylinder to each boiling tube, making sure the length and mass of each
cylinder is known. - Leave the cylinders in the boiling tubes overnight
- Remove the cylinders from the boiling tubes and carefully blot them dry with paper towels.
- Measure the length and mass of each cylinder and record your measurements
9.Calculate the percentage changes for each cylinder.
.
how could you avoid injury during osmosis rp
Take care when handling cork borer and sharp knife
how may someone get irregular results during osmosis rp
- Discs taken from different parts of the potato may have different water potentials.
- Potato discs may have different surface areas which affect the rate of osmosis.
How is the dna in cells that aren’t dividing
Spread out in long strings
Explain in detail the steps of mitosis
GROWTH
- the cell grows and increases the amount of subcellular structures like ribosomes and mitochondria
DNA SYNTHESIS
- duplicates its dna so theres one copy of each chromosome for each new cell
- forms x shaped chromosomes each arm is a duplicate of the other
MITOSIS
- chromosomes line up at the centre of the cell and are pulled apart be cell fibres
- membranes form around each opposite set of chromosomes these form the nuclei of the two cells
- cytoplasm and cell membrane divide
A scientist counts 120 cells in one field of view of those 42 are in the dna synthesis stage. In this particular cell one complete cycle lasts 24 hours. How long do they spend in the dna synthesis stage give your answer in minutes
- 24 X 60 = 1440 minutes
- 42/120 are in dna synthesis so…
- 42/120 X 1440 = 504 minutes
How do you calculate mitosis time
Number of cells in the stage [divided by] total number of cells [times] the total time of cell cycle
Describe the process of binary fission
- Circular dna and plasmids replicate
- The cell gets bigger and the circular dna strands mive to opposite ends of the cell
- The cytoplasm begins to divide and new cell walls begin to form
- The cytoplasm divides fully and two daughter cells are produced each daughter cell has one copy of circular sna but a varable number of plasmids
Why doesn’t binary fission create exact clones
Each daughter cell has one copy of circular dna but can have avariable number of plasmids
