1.2 Cell Structure

WJEC A-Level Biology

What does an animal cell that a plant cell does not?

Centrioles

What does a plant cell that an animal cell does not?

• Chloroplast

• Cellulose cell wall

• Permanent vacuole

Animal and plant cells diagrams

Nucleus

• contains genetic material

• controls all activity of cell

Chromatin - nucleus

dispersed genetic material

Nucleolus - nucleus

makes rRNA

Nuclear pores - nucleus

allows material to move in and out

Nuclear membrane - nucleus

double layered and continuous with endoplasmic reticulum

Endoplasmic reticulum

• network of membranes forming interconnected sacs called cisternae

• originates from outer membrane of nucleus

Rough endoplasmic reticulum

• ribosomes attached

• protein synthesis occurs

Smooth endoplasmic reticulum

synthesises lipids

Mitochondria

convert potential energy into ATP during aerobic respiration

Ribosome

• made up of large and small subunit

• involved in protein synthesis

• 70s ribosome in prokaryotes

• 80s ribosome in eukaryote

Golgi body

• formed by vesciles

• modifies and packages proteins

• forms lysosomes

• secretes carbohydrates

• produces secreting enzymes

Lysosome

• from the golgi body

• contains enzymes

• destroys and digests worn out material

Centrioles

• only animal cells

• found outside nucleus in centrosome

• forms spindle fibres for cell divison

Vacuole in plant cells

• large and permanent

• storage

• surrounded by tonoplast

Vacuole in animal cells

small and temporary

Cell wall

• only plant cells

• prevent osmotic bursting

• give cell strength and support

Plasmadesmarta

links plant cells together

Chloroplast

• only plant cells

• contains chlorphyll for photosynthesis

Prokaryotes

• found in bacteria

• no membrane-bound organelles

• DNA lies free in cytoplasm

• no nuclear membrane or ER

• small ribosomes (70s)

Eukaryotes

• plant/animal/fungi/protoctist

• membrane bound organelles

• DNA in chromosomes

• distinct nucleus

• large ribosomes (80s)

Ciliated columnar epithelium

• transport substances e.g. mucus in bronchi

• cilia move and sweep substances

• columnal

Cubodial epithelium

• lines the kidney tubules and small intestine

• cubed

Squamous epithelium

• flattened cells

• form walls of alveoli and bowmans capsule

Striated/skeletal muscle

• attached to bones

• bands of long fibres

• voluntary muscle tissue

Smooth muscle

• individual spindle shapes cells

• contract rhythmically

• skin/digestive/respiratory systems

• incoluntary muscles

Cardiac muscle

• found in heart

• contract rhythmically

• do not tire out

Connective tissues

• connect, support or separate tissues and organs

• elastic and collagen fibres

Virus structure