Biology - Cell Theory

Organelles in all living organisms

• Cytoplasm

• Ribosome

• Cell membrane

• DNA

Ultrastructure

The internal structure of cells

Animal cells only organelles

• Microvilli

• Centrioles

Plant Cells ONLY Organelles

• Chloroplasts

• Vacuole

• Cellulose Cell Wall

Microvilli

Folded regions of the cell surface membrane that increase cell surface area for absorption

Cell Surface Membrane Function

Controls the exchange of materials between the internal cell environment and the external environment

- ALWAYS say cell SURFACE membrane

What contains the nucleus?

a double membrane called the nuclear envelope

Nuclear pores - Function

• Allows mRNA and ribosomes to travel out of the nucleus

• Allows enzymes and signalling molecules to travel into the nucleus

What are chromosomes made from?

• chromatin

• Sections of linear DNA tightly wound around proteins called histones

Nucleolus function

ribosome production

Mitochondria Function

Site of aerobic respiration

What surrounds the mitochondria?

• A double membrane

• Inner membrane folded to form cristae

What does the matrix of mitochondria contain?

• Enzyms needed for aerobic respiration

miochondrial DNA

replication of mitochondria before cell division

Where can ribosomes be found?

• rough endoplasmic reticulum

• Cytoplasm

What are ribosomes?

Complex ribosomal RNA and proteins

Riboosome function

Site of translation

Size of ribosomes in eukaryotic cells

80s ribosomes

Size of ribosomes in prokaryotes

70s ribosomes

What organelles contain 70s ribosomes?

• mitochondria

• chloroplasts

Rough endoplasmic reticulum - what is it made of?

• folds of membrane continuous with the nuclear envelope

• surface covered in ribosomes

RER Function

process proteins made on the ribosomes

Smooth Endoplasmic Reticulum Function

the production, processing and storage of lipids, carbohydrates and steroids

SER - what is it made from?

• folds of membrane

• no ribosomes on surface

Golgi apparatus

• flattened sacs of membrane

• regular, stacked

Golgi Apparatus Function

• modify proteins and lipids

• packaging them into Golgi vesicles

• vesicles transport the proteins and lipids to their required destination

What makes up the lysosome?

• specialist forms of vesicle which contain hydrolytic enzymes

Lysosome Function

• break down waste materials such as worn-out organelles

• used by cells of the immune system and in apoptosis

Microtubules

• filaments of protein

• used to move substances around inside a cell

• to support the shape of a cell from the inside

Centrioles formed from what?

microtubules

Centriole Function

• Two centrioles at right angles to each other form a centrosome

• Centrosome organises the spindle fibres during cell division

Organelles

specialised parts of a cell that carry out a particular function