Human Biology Cells (2.1 & 2.2)

Cells…

are made of many components

Cytoplasm

thick fluid between cells & nucleus

it consists of organelles

Protoplasm

the nucleus & cytoplasm together

Cytosol

liquid part of the cytoplasm

made of a mixture of substances that dissolve in water; salt, carbon, oxygen, sugar

Cell Membrane

surronds the cell and seperates the cell contents from the external environment

controls what enter and leave the cell

Nucleus

controls all activity of a cell

contains DNA & RNA

Chromatin

when the cell isn’t dividing DNA is in long strands

Chromosomes

when the cell is dividing DNA chromatin thickens and coils to form chromosomes

Nucleolus

in the nucleolus

composed of RNA which has a role in protein synthesis

Nuclear Membrane

separates nucleus from cytoplasm

double membrane - separated by two walls with a space

there are gaps in the nuclear membrane called nuclear pores

Ribosomes

small, spherical organelles

where amino acids are joined together in a sequence determined by the DNA code

can be free or attached to endoplasmic reticulum in cytoplasm

Endoplasmic Reticulum (ER)

surface for chemical reactions

network of channels of parallel membranes used for transporting or storing

Smooth ER

without ribosomes attached

Rough ER

with ribosomes attached

Golgi Apparatus (Golgi Body)

a series of flattened membranous bags (often) stacked near the nucleus

purpose: to modify protiens and package for secretion (post office)

at the end of the membranous bag it pinches off to form vesicles (cyst, bladder, sac with waste or useful fluids)

vesicles migrate to the cell membrane and leave through exocytosis

Lysosomes

small spheres formed from the Golgi Apparatus

contains digestive enzymes

lysosomes fuse w/ vesicles and breack with down w/ digestive enzymes

Mitochondria

powerhouse of the cell

cellular respiration occurs

double membrane

in cytoplasm

cellular reactions release energy - curved surface to increase reaction surface area

has its own DNA

Cilia

small hairs, numerous (in trachea)

Flagella

one or two longer strands (sperm)

Inclusions

Chemical substances not part of the cell structure

Cytoskeleton

the frame work of protein fibres that give the cell its shape and assists cell movement