These notes contain everything from the IB Biology SL syllabus, including cellular biology, molecular biology, ecology, genetics, evolution and human physiology. Includes diagrams and charts as well. Super detailed, ensured I got a 7/7 on Biology.
Calculating Cell Size + Magnification
➔ Magnification = Image Size/Actual Size
➔ Actual Size = Image Size/Magnification
➔ 1 mm = 1000 µm
1 cm = 10 000 µm
Data processing and graphing
● Use a ruler to find values
● Never say “amount” or “size”
● When comparing - use at least 3 values on graph, X and Y
MICROSCOPY
Light microscopes
- illuminating source is light
- living or dead organisms
- up to 1500x magnification
- image is coloured
- lower resolution
Electron microscopes
- illuminating source is stream of electrons
- only dead organisms
- up to 300 000x magnification
- image is black and white
- higher resolution
, CELL BIOLOGY
Mitosis: division of nucleus into two genetically identical daughter nuclei
➔ Prophase: nucleus is still intact but envelope is gone, DNA is condensing, centrioles (only
in animal cells) begin to move
➔ Metaphase: chromosomes line up in middle of cell, centrioles on opposite ends of cell,
begin to produce spindle fibres/microtubules, attach to centromeres
➔ Anaphase: chromosomes move to far sides of cell, helped by spindles
➔ Telophase: chromosomes split up + become less visible, nuclear membrane forming
➔ Interphase → G1 - S - G2
- Makes up 90% of cell cycle
- Duplication of chromosomes into two sister chromatids
- G1: protein synthesis + replication of organelles + cytoplasm…
- G0: differentiated cell
- S: DNA replication/duplication/synthesis
- G2: replication of organelles etc. preparation for division
➔ Cytokinesis: cells divide fully
Organelles
➔ Cytoplasm: material within a cell containing organelles
➔ Nucleus: contains genetic material like DNA + controls activity of cell
➔ Cell wall: structural layer surrounding cell + providing support
➔ Ribosome: serves as site for protein synthesis
➔ Mitochondrion: supplies cellular energy + maintain control of cell cycle and growth
➔ Plasma membrane: layer of proteins + lipids forming boundary of cell + controls what comes
in/out
,➔ Endoplasmic Reticulum: membrane sacs/channels that modify + transport protein
◆ Rough ER: contains ribosomes, produces/transports/synthesises proteins
◆ Smooth ER: doesn't contain ribosomes, synthesises lipids
➔ Golgi body: responsible for processing + packaging protein into vesicles
➔ Vacuole: isolating harmful material + providing support + contains salt and sugar solutions +
maintains shape
➔ Chloroplast: contains chlorophyll + helps convert light into energy with photosynthesis
➔ Lysosomes: contains powerful digestive enzymes to break down + digest large molecules
★ go over electron microscopy of organelles
Plant vs Animal Cells
➔ Plants have cell walls, vacuoles + chloroplast
◆ Larger due to cell wall
◆ Synthesise glucose with photosynthesis
◆ store energy as starch grains
➔ Animal cells have lysosomes, small/no vacuole
◆ Cannot synthesise glucose
◆ Store energy as glycogen
animal cell
, plant cell
Eukaryotic vs Prokaryotic cells
Eukaryotic Prokaryotic
compartmentalisation no compartmentalisation
nucleus enclosed in nuclear membrane no defined nucleus; nucleoid region
cells divide by mitosis cells divide by binary fission
no capsule, pili or flagella capsule, pili and flagella
linear DNA as separate chromosomes single strand of coiled DNA in nucleoid region
ribosome 80S ribosome 70S
contain membrane-bound organelles do not contain membrane-bound organelles
FUNCTIONS OF LIFE
- Homeostasis: self-regulation + maintenance of stability/equilibrium in body functions
- Metabolism: chemical reactions involved in maintaining living state of cells + organism
- Growth: increase in cell size + number over lifespan of an organism
- Response: reaction to stimulus
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