Contents of the Cell Biology

Nucleus

Contains DNA of the cell. Surrounded by a nuclear envelope with two layers of membrane. Membrane layers are perforated with nuclear pores.

Nucleus i. Purpose of nuclear pores in double-layer membrane of nuclear envelope.

Entry sites for proteins from cytoplasm, exit points for mRNA for protein synthesis by ribosomes

Nucleus ii. Nucleolus

Region of the cell's DNA where ribosomes are made

Mitochondria

Generates energy in the form of ATP through aerobic cellular respiration from glucose.

Mitochondria i. Structure

Double membrane with a small oval body, inner membrane is greatly folded to provide a larger surface area, with folds being called cristae and the centre space between called the matrix.

Ribosomes

Not membrane bound organelles. They are the organelle in which proteins are synthesised; ribosomes read genetic code from mRNA (a single stranded RNA copied from DNA in nucleus)

Golgi apparatus

Packaging and modification for proteins and other polar compounds into vesicles (membrane bound sacs which fuse with membrane) for transport out of the cell.

Endoplasmic reticulum

Flattened, interconnected tubes and plates forming a continuous link with the nuclear membrane. Transports proteins within the cell, from the nucleus to cytosol.

ER i. Rough endoplasmic reticulum (rER)

Has ribosomes, synthesises and transports proteins within the cell

ER ii. Smooth endoplasmic reticulum (sER)

No ribosomes; synthesis and transport of lipids and steroids, detoxification of harmful compounds produced during metabolism.

Lysosome

Only in animal cells. Digests material from outside the cell (engulfed via endocytosis), breaks down foreign bodies and unwanted organelles, and apoptosis (controlled destruction of cell)

Chloroplasts

Plant cells only. Site of photosynthesis; traps light energy by chlorophyll molecule (green colour), produces organic molecules from CO2 and H2O using ATP as energy source.

Chloroplasts i. Structure

Enclosed by double membrane. Contains grana (disk-like stacks connected by lamellae) and stroma (basically cytoplasm for chloroplasts)

Flagella

Whip-like tails that assist with movement. Found in both prokaryotes and eukaryotic cells.

Cilia

Found in eukaryotes. Tiny, hair-like projections.

Cell inclusions (the non-living components) i. Animal cells

Water storage vacuoles, fat vacuoles, pigment-containing vacuoles, granules for secretion and/or storage

Cell inclusions (the non-living components) ii. Plant cells

Water storage vacuoles, plastids (stored carbohydrates such as starch, or chlorophyll - pigments, etc.), and cell wall.

Vacuoles - membrane bound?

Yes, by a single membrane called the tonoplast in plant cells.