Key Concepts in Biology
- Created by: Former Member
- Created on: 08-08-19 15:34
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- Section 1 - Key Concepts in Biology
- Cells
- Eukaryotic cells are complex and Prokaryotic cells are simple
- Suncellular structures
- Animal cells: nucleus, cytoplasm, cell membrane, mitochondria, ribosomes
- Plant cells also have: cell wall, vacuole, chloroplasts (photosynthesis)
- Bacterial cells: chromosomal DNA, ribosomes, cell membrane, plasmid DNA, flagellum
- Specialised Cells
- Structure makes them adapted to function
- egg cell: nutrients - cytoplasm, haploid nucleus, membrane stops any more sperm entering after fertilisation
- sperm cell: long tail, haploid nucleus, mitochondria, acrosome
- epithelial cells line organs - move substances
- nucleus of egg cell and sperm cell fuse - fertilised egg - embryo
- haploid cells combine - right number of chromosomes
- Structure makes them adapted to function
- Microscopy
- better resolution = more detail
- light microscope passes light through specimen to see sub-cellular structures
- electron microscopes have higher resolution and magnification
- total magnification = eyepiece lens magnification x objective lems magnification
- magnification = image size / real size
- standard form & unit conversion
- Enzymes
- biological catalysts - higher temperature
- key & lock - enzymes with active site have high specifity for substrate
- temperature increases reaction rate until a certain point - denatures
- optimum pH (often neutal 7)
- faster reaction with higher substrate concentration
- rate = 1000 / time
- Breakdown and Synthesis
- Proteins, Lipids, Carbohydrates broken down to digest easily
- carbohydrases > carbohydrates > simple sugars
- Protease > proteins > amino acids
- Lipases > lipids > glycerol & fatty acids
- Enzymes catalyse reactions needed to synthesise molecules from smaller components
- Diffusion, Osmosis, Active Transport
- Diffusion is the net movement of particles from an area of high concentration to an area of lower concentration
- Osmosis is the net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration
- Active transport is the movement of particles across a membrane against a concentration gradient using energy transferred during respiration
- Cells
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