B1 Cell Structure and Transport

Cell Membrane

surrounds a cell and controls what can enter or leave the cell

Cell Wall

Made of cellulose that strengthens and supports the cell.

Chloroplast

Contains chlorophyll and is responsible for carrying out photosynthesis.

Cytoplasm

a liquid gel where the organelles are held. Where most of the chemical reactions for life take place.

Mitochondria

Where aerobic respiration takes place releasing energy for the cell.

Nucleus

Controls all activites of the cell and contains the DNA for the cell.

Ribosomes

Where protein synthesis takes place.

Organelle

a tiny structure within a cell that performs a specific job

Vacuole

Filled with cell sap. Keeps the cell rigid to support the plant.

DNA

found in the nucleus - the material that carries all the information about how a living thing will look and function

Cells

the basic unit of life

Electron Microscope

- beam electrons
- very clear & high resolution
- black & white
- need dead specimen
- incredibly expensive
- very large

Light Microscope

- beams light
- not that clear / grainer / low resolution
- colour
- specimen can be alive
- quite small
- quite cheap

Magnification

size of image/size of real object

Organelles of Animal Cells

- cell membrane
- ribosomes
- cytoplasm
- mitochondria
- nucleus

Plant Cells

- cell wall
- chloroplasts
- vacuole
- cell membrane
- ribosomes
- cytoplasm
- mitochondria
- nucleus

Eukaryotic Cells

• Cell membrane

• Cell wall

• Cytoplasm

• Mitochondria

• Chloroplasts

• ribosomes

• DNA in nucleus

• Mitosis

Prokaryotic Cells

• Cell membrane

• Cell wall

• Cytoplasm

• Ribosomes

• No mitochondria and chloroplasts

• DNA found in single molecule in cytoplasm or rings called plasmids

• Binary fission

What is the prokaryotic cell wall composed of?

Peptidoglycan

How is DNA stored in a prokaryotic cell?

• Plasmid DNA

• Chromsomal DNA (Single loop of DNA)

Red Blood Cells Specialisation

- store & carry oxygen
- no nucleus for more space
- Biconcave shape for larger surface area

Muscle Cells Specialisation

• Special proteins that slide over each other making the fibres contract.

• Contain many mitochondria for muscle contraction.

• Store glycogen used for making energy.

Nerve Cells Specialisation

• Lots of dendrites to make connections to other nerve cells.

• Axon that carries nerve impulses.

• Lots of mitochondria to provide energy needed to make transmitter chemicals.

Sperm Specialisation

• Long tail for movement.

• Full of mitochondria which transfers the energy needed for the tail.

• Large nucleus containing genetic information.

• Digestive enzymes stored in acrosome for breaking down the outer layers of the egg.

Root hair cell specialisation

• Greatly increase surface area for water to move into the cell.

• Large permanent vacuole that speeds up movement of water by osmosis.

• Many mitochondria to transfer energy needed for active transport.

Photosynthetic cells specialisation.

• Contain chloroplasts containing chlorophyll that trap light.

• Large permanent vacuole keeps the cell rigid allowing the leaf to capture as much light as possible.

Xylem specialisation

• Lignin builds up in spirals in the cell walls. The cells die and form long hollow tubes that allow water and mineral ions to flow through.

Specialisation in Plants

- stem to support & transport
- leaves for photosynthesis
- roots for anchorage/ absorbing/ storage/ conduction

Diffusion

- movement of molecules from an area of higher concentration to an area of lower concentration
- from random movement
- passive progress
- in liquid & gases

Active transportation

- the movement of molecules from an area of lower concentration to an area of higher concentration
- requires energy ( from respiration)

Cell Diffusion

- oxygen gas molecules surrounding cells in a high concentration
- CO2 built up inside a cell in high concentration

Osmosis

The movement of water molecules from an area of high concentration to an area of low concentration through a partially permeable membrane.

Hypotonic

higher concentration of water inside the cell than outside ;
human - too dilute making the cell swell & burst
plant - suitable amount of water - normal & strong & standing up ( turgid)

Isotonic

balanced levels of water in & out of the cell
human - normal working cells
plant - not much water- floppy ( flaccid)

Hypertonic

lower concentration of water in the cell than outside
human- shrivels the cell
plant - not enough water- wilts & kills cell ( plasmolyse)

Osmosis Experiment with potato

- if the mass increases, water entered the potato ( or other)
- if the mass decreases, water left the potato
- water moves via osmosis
- osmosis is diffusion of water through a partially permeable membrane from a dilute (high levels of water) solution to a concentrated (low levels of water) solution
- the change is measured in percentage as the potatoes have different masses at the start of the experiment

What is a nanometre?

1 × 10^-9

What is a micrometre?

1 × 10^-6

Why is iodine used hen preparing a slide?

• It binds to starch in plant cells.

• It is a stain making cellular structures easier to see.