B2.1 Supplying The Cell Flashcards
Diffusion
Particles move down concentration gradient
Examples of diffusion
Gaseous exchange
Factors affecting diffusion
Distance particles have to travel
Steepness of concentration gradient
Surface area
Osmosis
Diffusion of water from high water potential to low water potential
High solute concentration - low water potential
Low solute concentration - high water potential
Plant osmosis
Too much water- turgor pressure high, cell is turgid
Too little water- turgor pressure low, cell is plasmolysed
Animal osmosis
Too much water- cell ruptures(lysis)
Too little water- cell crinkles(crenated)
Active transport
Transport against concentration gradient
ATP is needed
Make use of carrier proteins in cell membrane
Carrier protein
Molecules attach to the transport protein at cell membrane
Transport protein rotates and releases molecule inside cell using ATP
Transport protein rotates back and may use ATP again to do this
Examples of Active transport
Glucose to bloodstream
Nerve cell transport sodium in and potassium out
Plant root cells transport nitrate ions into cell
Mitosis
Cells divide for growth or repair
1) DNA replication
2) Movement of Chromosomes
3) cytokinesis
4) growth of daughter cell
Cell differentiation
When a cell becomes specialised to perform a specific job
Sperm cell
To transfer genetic material to ovary
Flagellum - to move to ovary
Lots of mitochondria- so it can get to ovary quicker
Acrosome- breaks down ovary outer layer to transfer genetic material
Fat cell
To store energy, insulate, protect organs
Small layer of cytoplasm around fat reservoir
Expand up to 1000x in size
Red Blood Cell
Transport oxygen around the body
Bioconcave- more surface area
Packed with haemoglobin- more oxygen
No nucleus- to carry more haemoglobin
Ciliated cell
Sticky mucus produced which traps dirt and bacteria
Cilia then weep away from airways to stomach
Palisade cells
To carry out photosynthesis
Packed with chloroplasts
Regular shape so more can fit on leaf
Stem cells
Undifferentiated cells that divide by mitosis so they can differentiate
Embryonic- can differentiate into any cell
Adult- can only differentiate into some cells
Stem cell uses
Stem cells can regenerate a liver from as little as 25% left
Adult stem cells only activate due to disease or tissue damage
Plant stem cells
Found in meristems (shoot tips)
Thin cell walls, small vacuole, no chloroplasts
