B1 - Cell Biology Flashcards
what is Active transport:
The movement of particles against a concentration gradient) with the use of energy from respiration.
what is an Adult stem cell
: A type of stem cell that can form many types of cells.
what is an Agar gel
A substance placed in petri dishes which is used to culture microorganisms on.
what is Cell differentiation:
The process where a cell becomes specialised to its function.
what is the Cell membrane
: A partially permeable barrier that surrounds the cell.
what is a Cell wall:
An outer layer made of cellulose that strengthens plant cells.
what is a Chloroplast
An organelle which is the site of photosynthesis.
what are Chromosomes:
DNA structures that are found in the nucleus which are made up of genes.
what is the Concentration gradient
The difference in concentration between two areas.
what is Diffusion
movement of particles from an area of higher concentration to an area of lower
concentration.✢
Embryonic stem cell:
A type of stem cell that can differentiate into most types of human
cells.
Eukaryotic cell
A type of cell found in plants and animals that contains a nucleus.
Magnification
How much bigger an image appears compared to the original object.
Meristematic cells:
A type of stem cell that can differentiate into any type of plant cell.
Mitochondria
An organelle which is the site of respiration.
what is Mitosis
A type of cell division which produces two genetically identical daughter cells from
one parent cell.
Nucleus:
An organelle found in most eukaryotic cells that contains the genetic material of the
cell and controls the activities of the cell.
Organelle
A specialised structure found inside a cell.
what is Osmosis:
The diffusion of water from a dilute solution to a concentrated solution through a
partially permeable membrane.
what is a Plasmid:
Loops of DNA found in the cytoplasm of prokaryotic cells.
Prokaryotic cell
A type of cell found in bacteria that does not contain a nucleus
Resolution:
The ability to distinguish two different points in a specimen.
Specialised cells
Cells that are adapted to perform a specific function.
Stem cell:
: An undifferentiated cell that can divide to produce many specialised cells of the
same type.
Surface area to volume ratio
The size of the object compared with the amount of
area where it contacts its environment.
The cell cycle:
A series of stages preparing the cell for division.
Therapeutic cloning
Producing an embryo that has the same genes as a patient.
Vacuole
An organelle that stores cell sap.
what are the two types of cells
1) eukaryotic (plant and animal)
2)prokaryotic (bacteria)
what are the differenced between eukaryotic and prokaryotic cells
prokaryotic cells are much smaller than eukaryotic cells. Eukaryotic cells contain membrane bound - organelles and a nucleus containing genetic material, while prokaryotes do not
how is genetic information stored in a prokaryotic cell
found free within the cytoplasm as: chromosomal DNA , plasmid DNA
what are plasmids
1) small, circular loops of DNA found free in the cytoplasm and separate from the main DNA
2)carry genes that provide genetic advantages such as antibiotic resistance
lists components of both animal and plant cell
nucleus, cytoplasm, cell membrane, mitochondria, ribosomes
list additional cell components of a plant cell
chloroplasts, vacuole, cell wall
what is the function of a nucleus
controls cells activities
describe the structure of the cytoplasm
1) fluid component of the cell
2) contains organelles, enzymes and dissolved ions and nutrients
what is the function of the cytoplasm
site of cellular reactions e.g first stage of respiration
what is the function of the cell membrane
controls the entry and exits of materials in and out of the cell
what is the function of the mitochondria
site of later stages of aerobic respiration
what is the function of ribosomes
joins amino acids in a specific order
what is the plant cell wall made of
cellulose
what is the function of the plant cell wall
1 ) provides strength
2 )
what does the permanent vacuole contain
cell sap( a solution of salts, sugars and organic acids )
what is the function of the permanent vacuole
supports the cell
what is the function of chloroplasts
site of photosynthesis
describe how sperm cells in animals are adapted to their function
haploid nucleus contains genetic information
tail enables movement
mitochondria provides energy for tail movement
acrosome contains enzymes that digest the egg cell membrane
describe how nerve cells in animals are adapted to their function
1) long axon allows electrical impulses to be transmitted all over the body
2) dendrites from the cell body connect to and receive impulses from other nerve cells ,muscles and glands
describe how muscle cells are adapted to their function
1) arrangement of protein filaments allows them to slide over each other to produce muscle contraction
2) mitochondria to provide energy for muscle contraction
describe how roots cells in plants are adapted to their function
1) large surface area to absorb nutrients and water from soil
2) thin walls that do not restrict water absorption
describe how xylem cells in plants are adapted to their function
1) no margins between cells to provide a continuous route for water to flow
2)thick , woody side walls strengthen their structure
describe how phloem cells in plants are adapted to their function
1)sieve plates let dissolved amino acids and sugars be transported up and down the stem
2)companion cells provide energy needed for active transport
what is cell differentiation
the process which cells become specialised
why is cell differentiation important
allows production of different tissues and organs that perform various vital functions in the human body
what is the purpose of cell division in mature animals
repair and replacement of cells
what changes does a cell go through as it differentiates
becomes specialised through acquisition of different sub-cellular structures to enable a specific function to be performed by the cell
Define magnification
The number of times bigger an image appears compared to the size of the real object.
what are the advantages of light microscopes?
● Inexpensive
● Easy to use
● Portable
● Observe both dead and living specimens
what is the disadvantage of light microscopes?
Limited resolution
How does an electron microscope work?
It uses a beam of electrons which are focused using magnets. The electrons hit a fluorescent screen which emits visible light, producing an image.
what is the advantage of electron microscopes?
Greater magnification and resolution
how have elctronmicroscopes enabled scientists to develop their understanding of cells?
- allow small sub-cellular structures (eg mitochondria, ribosomes) to be observed in detail
- enable scientists to develop more accurate explanations about how cell structure relates to function
what are the disadvantages of electron microscopes?
- expensive
- large so less portable
- require training to use
- only dead specimens can be observed
how do bacteria multiply?
Binary fission (simple cell division)
State 2 ways in which bacteria can be grown
● Nutrient broth solution
● Colonies on an agar gel plate
what is diffusion?
the net movement of particles from an area of higher concentration to an area of lower concentration
what three main factors affect the rate of diffusion?
concentration gradient - larger gradient, faster diffusion
temperature - higher temperature, faster diffusion
surface afea - larger surface area, faster diffusion
give examples of substances transported by diffusion in the lungs
lungs - oxygen diffuses into the blood from the lungs and carbon dioxide diffuses into the lungs from the blood, both down their concentration gradient
How are single-celled organisms adapted for diffusion?
they have a large surface area to volume ratio - maximises the rate of diffusion of molecules to meet the organisms needs
What is osmosis?
the movement of water from a dilute solution to a concentrated solution through a partially permeable membrane
What is active transport?
the movement of molecules from a more dilute solution to a more concentrated solution against a concentration gradient, using energy from respiration
How do plant root hair cells use active transport?
Root hair cells use active transport to take up mineral ions from a more dilute solution in soils. Ions such as magnesium and nitrates are required for healthy growth.
how is active transport used to absorb the products of digestion?
active transport is used to transport glucose from a lower concentration in the gut to a higher concentration in the blood. glucose is then transported to the tissues where it can be used in respiration
what are uncontaminated cultures of microorganisms needed for
investigating disinfectant and antibiotic action
How do you prepare an uncontaminated culture using aseptic technique?
1) Sterilize petri dish / bacterial nutrient broth / agar
2) Pass inoculating loop through flame
3) Using inoculating loop - transfer bacteria to petri dish
4) Attach petri dish lid using adhesive tap
5)Place agar plate upside down into incubator
Why do we sterilize the petri dish
to kill unwanted microorganisms
Why do we pass the inoculating loop through a flame
it sterilizes the loop
Why do we attach the petri dish lid using adhesive tap?
to stop microorganisms in the air getting in
Why do we place the agar plate upside down
Because it stops condensation
Why do we incubate bacteria at 25* in schools
reduces chance of harmful bacteria growing
what are chromosomes made of
chromosomes consist of DNA molecules combines with proteins .They contain genes which provide instructions for protein synthesis
what is a gene
a section of DNA which codes for a protein
how many chromosomes are found in the nucleus of human body cells
46
how many chromosomes are found in the nucleus of gametes
23
what are the three main stages of the cell cycle
1) replication of DNA and synthesis of organelles
2) mitosis
3) division of cell
why is mitosis important
produced identical cells which all have the same information , produces additional cells for growth and repair
describe the first stage of the cell cycle
cells grow and increase in mass, replicate DNA and synthesise more organelles e.g. mitochondria , ribosomes
describe the second stage of the cell cycle
each chromosome in a pair is pulled to opposite poles of the cell, then the nucleus divides
describe the third stage in the cell cycle
the cytoplasm and the cell membrane divide - two identical daughter cells are produce
what is a stem cell
an unspecialised cell which is capable of differentiating into other cell types
what is the function of stem cells in embryos
embryonic stem cells can replicate themselves and differentiate into many other types of cells. Embryonic stem cells may be able to treat conditions such as diabetes by dividing to replace damaged cells
what is the function of stem cells in adult bone marrow
adult stem cells can differentiate into several cell types to replace dead or damaged tissues
what is the function of stem cells in plant meristems
meristem stem cells can differentiate into any cell which is required by the plant
what is therapeutic cloning
a cloning method where an embryo is produced which the same genetic makeup as the patient .The stem cells which originate from the embryo will not be rejected by the patients immune system, so can be used to treat certain medical conditions
what are advantages of cloning plants using meristem tissues
1) can prevent rare plants from becoming extinct
2) can produce identical plants for research
what are issues associated with the use of stem cells
1) if donor stem cells do not have a similar genetic makeup to the patient ,an immune response could be triggered
2) adult stem cells infected with virus could transfer infections to patient
how are single - celled organisms adapted for diffusion
they have a large surface area to volume ratio
what 4 factors increase the effectiveness if a gas exchange surface
1) large surface area
2) thin membrane - short diffusion path
3) efficient blood supply
4) ventilation
what is it meant when a solution is isotonic to a cell
the concentrations of the external and internal solutions are the same
what is mean when a solution is hypertonic to a cell
the concentration of the external solution is higher that the internal solution
