GCSE Revision 1/7 Flashcards
Nucleus
Carries instructions for making proteins
Cytoplasm
Where organelles are suspended, and where chemical reactions take place
Cell membrane
Controls movement of substances into and out of the cell
Mitochondria
Where energy is transferred during aerobic respiration
Ribosomes
Where protein synthesis occurs
Cell wall
Support
Chloroplasts
Contain chlorophyll for photosynthesis
Permanent vacuole
Stores cell sap keeping the cell rigid
Prokaryotic cells features (5)
Cell membrane, cell wall, no nucleus (plasmids instead), cytoplasm, slime capsule/flagella
Specialisation in Nerve cells (4)
Many dendrites to make connections to other nerve cells
Axons to carry impulses from one place to another
Synapses which pass impulses to other cells through chemicals
Mitochondria in synapses to transfer energy needed for neurotransmitters
Specialisation in muscle cells (3)
Special proteins that slide over eachother
Many mitochondria to transfer required energy for chemical reactions
Store of glycogen that can be broken down and used in respiration
Specialisation in sperm cells (4)
Long tail that propels the sperm
Middle section full of mitochondria to transfer energy needed to move
Acrosome to store digestive enzymes to break down outer layers of the egg (at the tip)
Large nucleus containing the genetic information
Specialisation in root hair cells (3)
Large SA for water to move into the cell
Large permanent vacuole to speed up movement of water
Mitochondria to transfer energy for active transport of mineral ions
Specialisation in photosynthetic cells (3)
Chloroplasts with chlorophyll to trap light needed for photosynthesis
Often found in continuous layers in the leaf and outer layers of stems (at the surface)
Have a large permanent vacuole that helps keep the cell rigid
Specialisation in xylem cells [transport of water and mineral ions and structural support] (2)
Long hollow tubes for water and mineral ions to move up through
Spirals of lignin make the xylem tubes very strong
Specialisation in phloem cells (3)
Sieve plates (made from broken down cell walls) to move phloem sap by translocation through the plant
Companion cells with mitochondria that transfer energy to aid in this movement of phloem sap
Osmosis across
Partially permeable membrane
Same concentration of solutions
Isotonic
More concentrated solution
Hypertonic
Less concentrated solution
Hypotonic
Turgor pressure
When no more water can enter the cell
How does a cell become turgid (4)
Water moves in by osmosis
Vacuole swells
Cytoplasm is pressed against the cell wall
Cell becomes rigid
What is the opposite of turgid
Flaccid
Plasmolysis
When plant cells lose so much water that the vacuole and cytoplasm shrink and the cell membrane pulls away from the cell wall
Active transport
Diffusion against a concentration gradient- requires energy
How does active transport occur (3)
Molecule binds to transport protein
Protein rotates and releases molecule inside cell (E)
Cell rotates back again (E)
Relationship between SA and V depending on size
As size increases, the ratio decreases
Cell cycle stage 1 - Interphase (3)
The longest stage, cells grow, increase in mass, and carry out normal activities
The cells then replicate their DNA to make two copies of of every chromatin strand in the nucleus
They also make more sub-cellular structures in the cell
Cell cycle stage 2 - Mitosis (5)
Chromatin condenses and coils to form chromosomes
Nucleus Disintegrates
Chromosomes line up in the centre of the cell
Spindle apparatus pulls identical chromosomes to opposite ends of the cell
Nucleus returns
Cell cycle stage 3- Cytokinesis (1)
Cytoplasm and the cell divides in half to form two identical daughter cells
How many chromosomes do human body cells have
46 (23 pairs) DIPLOID
What are egg and sperm cells also known as
Gametes
How many chromosomes do egg and sperm cells have
23 each HAPLOID
Stem Cells and where are they found in animals and plants
Cells that haven’t yet specialised. Found in animal embryos and plant meristems
Where do adult stem cells do
Provide a backup of specialised cells if the ones that were made at birth don’t work anymore (these can’t divide by mitosis)
How can you make more specialised cells without stem cells?
Embryo cloning- making a clone of a person and culturing the embryonic stem cells to create specialised cells
What can stem cells help with (2)
Paralysis by differentiating into new nerve cells
Diabetes- producing cells that are sensitive to blood sugar and can produce insulin
What is a meristem
Actively dividing groups of plant tissues found at the tips of plants
How can stem cells be used in plants (4)
Save rare plants from extinction
Create genetically identical plants for scientific research
Produce large numbers of exotic plants for sale
Plants with special features can be cloned
Stem cell dilemmas (4)
Violation of the embryo’s rights (ethical)
Not interfere with the natural processes of reproduction (religious)
A lot of money is wasted on research which could be used in other things (ethical and social)
Embryonic stem cells could cause cancer as they divide rapidly
Therapeutic cloning
A process where an embryo is produced that is genetically identical to the patient so the cells can then be used in medical treatment
