B1 Cell Structure and Transport Flashcards
What are the two types of microscopes?
Light microscope and electron microscope
How to calculate magnification?
Magnification = Size of image / size of real object
What is the magnification of light microscopes?
Up to about x2000, and have a resolving power (detail) of about 200nm
What is the magnification of electron microscopes?
Up to about x2,000,000 and have a resolving power (detail) of around 0.2nm
What are the organelles in an animal cell?
- Cell membrane
- Ribosome
- Nucleus
- Cytoplasm
- Mitochondria
What are the organelles in a plant cell?
- Cell membrane
- Ribosome
- Nucleus
- Cytoplasm
- Mitochondria
- Cell wall
- Vacuole
- Chloroplast
What is the function of the nucleus?
- Control the activities of the cell
- Contains the genes and chromosomes needed to make new cells and organisms
What is the function of the cytoplasm?
A liquid gel where most of the chemical reactions for the cell happen
What is the function of the cell membrane?
Controls what enters and leaves the cell
What is the function of the mitochondria?
Where respiration occurs. Oxygen and glucose react to release energy
What is the function of the ribosomes?
Where protein synthesis takes place. All proteins needed in a cell are made here.
Why do plant cells have more organelles than animal cells?
Plants need to make their own food
What is the function of the cell wall?
Made of cellulose. Gives the cell structure and the plant strength and support
What is the function of the chloroplast?
It is what makes the plant green. Also where photosynthesis takes place
What is the function of the permanent vacuole?
Keeps the plant rigid and filled with sap (storage of material)
The beginning of life on Earth
Began with a single-celled organism-like bacteria called prokaryotic cells. After millions of years, through evolution, eukaryotic cells came into being
Prokaryotic cells
- Do not have “membrane-bound organelles”
- No distinct nucleus, mitochondria, chloroplasts or any other internal organelles in the same way plant and animal cells do
What are the organelles in a prokaryotic cell?
- Cell wall
- Cell membrane
- Ribosomes
- Cytoplasm
- Genetic Material
- Flagella
Order of magnitude
Number of zeros - 10x OM of 1
if the number doesn’t end with a zero, round it to the nearest order. E.g. 12x is close to 10x than 100x so OM of 1
What are specialised cells?
In multicellular organisms, cells specialise so that they are very good at carrying out a particular function -> need adaptations. This is called differentiation
Function of the nerve cell (Neurone)
Carry electrical signals around the body providing a rapid communication system between the different parts of the body
Adaptations of the nerve cell (Neurone)
- Lots of connections to other nerve cells (Dendrites)
- Very long axon -> carry electrical signals
- Lots of mitochondria to provide the energy needed
- Synapse -> connect neurons to help transmit information from one neuron to the next
Function of the muscle cell
Contract to bring about movement
Adaptations of the muscle cell
- Special proteins that slide over each other making fibres contract
- Many mitochondria for respiration to produce energy
- Store glycogen -> chemical that can be broken down and used in respiration by the mitochondria if needed.
Function of the sperm cell
Transfer genetic information from the male parent during reproduction
Adaptations of the sperm cell
- Long tail to help the sperm move
- Lots of mitochondria to transfer energy to the tail
- Head stores enzymes to break down the outer layer of the egg cell
- Nucleus to store genetic information
Function of the root hair cell
Absorb water and mineral ions
Adaptations of the root hair cell
- Large surface area -> increases rate of diffusion and active transport
- Large permanent vacuole that speeds up the movement of water by osmosis
- Lots of mitochondria that transfer energy needed for the active transport of mineral ions into the root hair cells
Function of the photosynthetic cell
Make food using photosynthesis
Adaptations of the photosynthetic cell
- Contain chloroplasts -> Where photosynthesis work
- Large permanent vacuole to help keep the cell rigid as a result of osmosis. This helps support the stem and keeps the leaf spread out.
- Regular shape -> Has a cell wall and vacuole to keep it rigid
Function of the xylem cell
Carries water and mineral ions from roots to all leaves and shoots
Adaptations of the xylem cell
- Lignin to strengthen
- Cells die and form hollow tubes allowing water to move easily through them
Function of the phloem cell
Carries food (sugar) made from photosynthesis around the plant
Adaptations of the phloem cell
- Cell walls between cells break down to form special sieve plates (like a colander)
- Lose a lot of the internal structure but are supported by companion cells that keep them alive
- Mitochondria of the companion cells transfer the energy needed to move the food
What is diffusion?
The movement of particles from a high to low concentration
Factors to speed up diffusion
- Temperature
- Bigger surface area
- Higher concentration gradient
How does an increase in temperature speed up the rate of diffusion?
The higher the temperature, the more energy the particles will have, increasing their random movement.
What is osmosis?
The net movement of water from a high to low water concentration through a partially permeable membrane -> dilute to concentration solution
What causes water to move in or out of a cell?
Differences in the concentrations of solutions inside and outside a cell cause movement via osmosis
How can animal cells be damaged from osmosis?
When the concentration outside the cell changed dramatically. E.g. pouring salt on a slug causes it to die from osmosis
