Topic 1 - Cell biology Flashcards
Name 5 subcellular structures that both plant and animal cells have (and their purpose)
Nucleus - contains DNA
Cytoplasm - where chemical reactions happen
Cell membrane - controls what goes in and out
Mitochondria - where respiration happens (transfers energy)
Ribosomes - where proteins are made
Name 3 subcellular structures that just plant cells have (and their purpose)
Cell wall - supports cell
Vacuole - contains cell sap
Chloroplasts - where photosynthesis occurs
Are plant and animal cells prokaryotic or eukaryotic?
Eukaryotic
Are bacteria cells prokaryotic or eukaryotic?
Prokaryotic
Define cells
Cells are basic units that make up a living organism
State some similarities between prokaryotic and eukaryotic cells
They both have DNA, a cell wall, ribosomes and a cell membrane
State some differences between prokaryotic and eukaryotic cells
E has its DNA enclosed in a nucleus whereas P is just in its cytoplasm.
E is complex and uni or multicellular whereas P is simpler and always unicellular (and smaller)
Define magnification
how much bigger a sample appears to be under the microscope than it is in real life
Define resolution
the ability to distinguish between two points on an image - the amount of detail
What is the formula for magnification?
magnification = image/actual size
Define aseptic technique
taking steps to avoid contamination from pathogens
Define diploid
A full set of chromosomes (46)
Define chromatid
A copy of a chromosome
Explain the growth and DNA replication stage of the cell cycle
The DNA is spread out in long strings. It grows and increases the amount of subcellular structures it has. It then duplicates its DNA so there’s one copy for each new cell, creating an X-shaped chromosome
Explain the mitosis stage of the cell cycle
The chromosomes line up at the centre of the cell and cell fibres pull them apart to opposite ends of the cell. Membranes form around each of the new sets of chromosomes. The cell has produced two daughter cells (which are identical to each other and to the parent cell).
How are stem cells different to regular cells?
They are non-specialised so they can become any cell
How are adult and embryonic stem cells different?
Embryonic stem cells can become any cell but adult stem cells can only become some cells
Name some sources of human stem cells:
-embryos
-bone marrow
-therapeutic cloning
Define differentiation
the process by which a cell changes to become specialised for its job
Give two uses of stem cells in animals
-treat diseases
-replace organs/tissues
Give two uses of stem cells in plants
-grow rare species
-improve features of plants
Give reasons for and against embryonic stem cells
For:
-legally still just a bunch of cells
-could find cures
-could replace humans in testing processes (e.g for new drug)
Against:
-destroys a potential life
-no-one dies if you use adult stem cells
Define diffusion
the movement from an area of high concentration to an area of low concentration (down a concentration gradient)
How does distance affect the rate of diffusion?
if the particles have to travel further, it’s going to take longer and the particles are going to lose energy so rate of diffusion is slowed
How does concentration gradient affect the rate of diffusion?
when there’s a larger concentration gradient, there are more particles which means more energy which means faster diffusion
How does surface area affect the rate of diffusion?
when there’s a bigger surface area, there are more places for the particles to move into which means more particles can diffuse at the same time
How does temperature affect the rate of diffusion?
higher temp means more energy so the particles will move faster
Name the 4 common features of all exchange surfaces:
-big surface area
-thin (short distance for diffusion)
-moist (allows substances to dissolve)
-a means of maintaining a steep concentration gradient to speed up diffusion
Define concentration gradient
the difference in concentration between two areas
Define osmosis
the diffusion of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration
- [mention water 3 times]
Define a partially permeable membrane
it has small holes in it that permit small water molecules through
Define dilute
Dilute solutions have a high concentration of water molecules
Define concentrated
Concentrated solutions have a low concentration of water molecules
What would happen if a blood cell was put it in distilled water?
It would swell and burst because the water molecules would diffuse into the cell so they can move away from the high water concentration outside and into the low water concentration inside
What would happen if a blood cell was put in a concentrated solution?
It would shrink and shrivel because water would diffuse out of the cell because the is a lower water concentration outside the cell so it moves from a higher water concentration inside the cell
What is the formula for calculating percentage mass?
change/original value x 100
