1.1 Cell biology

Prokaryotes

Cells without a nucleus, smaller, simpler cells (bacteria)

Eukaryotes

Cells with a nucleus and membrane-bound organelles

Cell membrane

Controls what enters and leaves the cell

Cytoplasm

Where chemical reactions occur in the cell

Nucleus

Contains genetic material (DNA)

Bacterial cell features

Cell wall, cell membrane, cytoplasm, circular DNA, plasmids

Plasmid

Small ring of DNA in bacterial cells

Organelles

Structures in cells with specific functions

Magnification calculation

Magnification = image size ÷ actual size

Chloroplasts

Where photosynthesis occurs in plant cells

Chlorophyll

Green pigment that absorbs light energy for photosynthesis

Permanent vacuole

Contains cell sap and keeps cell rigid

Cell wall (plants)

Made of cellulose, strengthens the cell

Cell differentiation

Process where cells become specialised

Stem cells

Undifferentiated cells that can become different cell types

Sperm cell adaptation

Streamlined, tail for movement, many mitochondria, enzymes in acrosome

Nerve cell adaptation

Long axon, branched dendrites, many mitochondria

Muscle cell adaptation

Many mitochondria, contractile proteins, stores glycogen

Root hair cell adaptation

Large surface area, many mitochondria, large vacuole

Xylem function

Transports water and minerals up the plant

Phloem function

Transports sugars around the plant

Xylem structure

Dead hollow tubes with lignin for support

Phloem structure

Sieve tubes and companion cells

Light microscope

Uses light, magnifies up to ~2000x, used for cells/tissues

Electron microscope

Uses electrons, higher magnification and resolution

Resolution

Ability to distinguish between two points

Standard form

Writing very large or small numbers using powers of 10

Culture medium

Provides nutrients for microorganisms to grow

Agar plate

Gel used to grow bacteria colonies

Sterilisation

Kills unwanted microorganisms to prevent contamination

Binary fission

Bacteria reproduction by splitting into two

Colony

Group of bacteria visible on agar

Antibiotic resistance

Bacteria survive antibiotics due to mutations

Cell cycle

Interphase, mitosis, cytokinesis

Interphase

Growth and DNA replication stage

Mitosis

Chromosomes separate into identical nuclei

Cytokinesis

Cytoplasm divides forming two cells

Stem cell benefit

Can treat diseases and repair damaged tissue

Stem cell risk

Ethical concerns and possible tumour formation

Diffusion

Movement from high to low concentration

Concentration gradient

Difference in concentration between two areas

Oxygen diffusion

Oxygen moves from alveoli into blood

Gas exchange

Exchange of oxygen and carbon dioxide in lungs

Surface area to volume ratio

Comparison of surface area to volume of organism

Osmosis

Movement of water from high to low water potential

Water potential

Measure of water concentration in a solution

Hypotonic solution

More dilute solution, water enters cell

Hypertonic solution

More concentrated solution, water leaves cell

Isotonic solution

Equal concentration, no net movement of water

Turgid plant cell

Plant cell swollen with water, firm and rigid

Plasmolysis

Cell membrane pulls away from cell wall due to water loss

Active transport

Movement against concentration gradient using energy

Root hair active transport

Absorbs mineral ions from soil using energy

Gut active transport

Absorbs glucose and amino acids into blood

Cell membrane function

Controls movement of substances in and out of cell

Microscopy use

To view cells and sub-cellular structures

Cell specialisation

Cells adapted for specific functions

Chloroplast function

Absorbs light energy for photosynthesis

Nucleus function

Controls cell activities using DNA