B1 Cell biology Flashcards
what subcellular structures are in an animal cell?
- nucleus
- cytoplasm
- cell membrane
- mitochondria
- ribosomes
what subcelluar structures are in a plant cell?
- nucleus
- cytoplasm
- cell membrane
- mitochondria
- ribosomes
- rigid cell wall
- permanent vacuole
- chloroplasts
describe the nucleus
contains genetic material that controls the activities of the cell
describe the cytoplasm
gel-like substance where most of the chemical reactions happen
it contains enzymes that control these chemical reactions
describe the cell membrane
this holds the cell together and controls what goes in and out
describe mitochondria
most of the reactions for aerobic respiration takes place
respiration transfers energy that the cell needs to work
describe ribosomes
this is where proteins are made in the cell
describe the rigid cell wall
made of cellulose
it supports the cell and strengthens it
describe the permanent vacuole
contains cell sap, a weak solution of sugars and salts
describe chloroplasts
where photosynthesis occurs, which makes green substance called chlorophyll, which absorbs the light needed for photosynthesis
what are eukaryotic cell?
eukaryotes are organisms that are made up of eukaryotic cells
what are prokaryote cells?
it is a prokaryotic cell (its a single-celled organism)
what cell is bacteria?
bacteria is prokaryotes
what subcellular structures does bacteria contain?
- cell membrane
- single circular strand of DNA that floats freely in the cytoplasm (doesn’t have a nucleus)
- small rings of DNA called plasmids
- cell wall
- cytoplasm
what is the equation for magnification?
magnification = image size / real size
what is differentiation?
the process by which a cell changes to become specialised for its job
as cells change, they develop different subcellular structures and turn into different types of cells
give examples of specialised cells
- sperm cells
- nerve cells
- muscle cells
- root hair cells
- phloem and xylem cells
what are sperm cells specialised for?
reproduction
what are nerve cells specialised for?
rapid signalling
what are muscle cells specialised for?
contraction
what are root hair cells specialised for?
absorbing water and minerals
what are phloem and xylem cells specialised for?
transporting substances
describe the function of sperm cells
to get the male DNA to the female DNA
it has a long tail and a streamlined head to help it swim to the egg
there are lots of mitochondria in the cell to provide the energy needed
it also carries enzymes in its head to digest through the egg cell membrane
describe the function of nerve cells
to carry electrical signals from one part of the body to another. these cells are long (to cover more distance) and have branched connections at there ends to connect to other nerve cells and form a network throughout the body
describe the function of muscle cells
to contact quickly
these cells are long (so they have space to contract) and contain lots of mitochondria to generate the energy needed for contraction
describe the function of root hair cells
root hair cells are cells on the surface of plant roots, which grow into long “hairs” that stick out into the soil
this gives the pants big surface area for absorbing water and mineral ions from the soil
describe the function of phloem and xylem cells
from phloem and xylem tubes, which transport substances such as food and water around plants. to form the tubes, the cells are long and joined end to end. xylem cells are hollow in the centre and phloem cells have very few subcellular structures, so that stuff flow through them
what is diffusion?
it is the spreading out of particles from an area of higher concentration to an area of lower concentration
what is osmosis?
the movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration
how many chromosomes do body cells have?
they normally have 2 copies of each chromosome - one from the organisms mother and one from its father
what is the cel cycle?
body cells on multicellular organisms divide to produce new cells as part of a series called the cell cycle
what is mitosis?
the stage of the cell cycle when the cell divides
what are the 2 main stages of the cell cycle?
- growth and DNA replication
- mitosis
growth and DNA replication is the fist part of the cell cycle
describe this
1) DNA is spread out in long strings
2) before it divides, the cell has to grow and increase the amount of subcellular structures such as mitochondria and ribosomes
3) it duplicates its DNA - one copy for each cell. the DNA is copied and forms X shaped chromosomes. each “arm” of the chromosomes is an exact duplicate of the other
mitosis is the second part of the cell cycle
describe this
once it has gone through growth and DNA replication
its ready for mitosis…
1) chromosomes line up and cell fibres pull hem apart. the 2 arms of each chromosomes go to the opposite ends of the cell
2) membranes form around each of the sets of chromosomes. these become the nuclei of the 2 new cells - the nucleus is divided
3) lastly, the cytoplasm and cell membrane divide. the cell has now produced two new daughter - contain the same DNA - identical. their DNA is also identical to the parent cell
what does medicine already use adult stem cells for?
to cure disease
where does diffusion happen?
in both solutions and gases- because the particles in these substances are free to move about randomly
the bigger the concentration gradient (the difference in concentration) ……
the faster the diffusion rate
a higher temperature will ……
give a faster diffusion because the particles have more energy, s move around faster
how is the cell membrane clever?
- the hold the cell together but they let suff in and out as well
- dissolved substances can move in and out of cells by diffusion
what is the job of the lungs?
it is to transfer oxygen to the blood and to remove waste carbon dioxide from it
to do this the lungs contain millions of little air sacs called alveoli where gas exchange takes place
when is active transport used in the gut?
when there is a lower concentration of nutrients in the gut but a higher concentration of nutrients in the blood
when does active transport diffuse naturally into the blood?
when theres a higher concentration of glucose and amino acids in the gut
what happens when the active transport concentration gradient is the wrong way?
when theres a lower concentration of nutrients in the gut than there is in the blood
describe root hair cells
- cells on the plant roots grow into “hairs” which stick out into the soil
- each branch covers millions of these microscopic hairs
- means there is a large surface are for absorbing water and mineral ions from the soil
- plants need mineral ions for healthy growth
- concentration of minerals is usually higher in the root hair cells than in the soil around them
describe the practical of the effect of sugar solutions on plant tissue
- cut into potato into identical cylinders
- beakers with different sugar solutions in them
- one should be pure water and a very concentrated sugar solution
- cut into potato into identical cylinders
- measure mass of cylinder, then leave one cylinder in each beaker for 24 hours
3) - take them out, dry with paper towel and measure masses again
- measure mass of cylinder, then leave one cylinder in each beaker for 24 hours
4) - cylinders have drawn in water by osmosis = increased in mass
- water has been drawn out = decreased in mass
- calculate percentage change in mass, plot graphs
5) dependent variable = chip mass
independent variable = concentration of the sugar solution
- all of variables must be kept the same in each case or the experiment won’t be a fair test
- may be some errors, reduce the effect of these errors by repeating the experiment and calculating a mean percentage change at each concentration
how are the alveoli specialised?
to maximise the diffusion of oxygen and carbon dioxide they have: - an enormous surface area - a moist lining for dissolving gases - very thin walls - a good blood supply
what is inside the small intestine?
covered in millions and millions of these tiny little projections called villi
- increase surface area so that digested food is absorbed much more quickly into the blood
they have:
- a single layer of surface cells
- a very good blood supply to assist quick absorption
