Cell Structure

Cell Membrane

The outer boundary of the cell separating it from neighbouring cells and the external environment.

\-Made of a double layer of lipids molecules and associated proteins.

\-Determines what enters and exits the cell.

Nucleus / Nucleoplasm

Controls the structure of the cell and the way it functions

\-contains genetic material, primarily DNA

\-usually ovoid or spherical

\-separated from the cytoplasm by **nuclear membrane**, which has nuclear pores that allow in large molecules

Ribosomes

Where amino acids are joined together to make proteins

\-very small and spherical

\-can be free in the cytoplasm but most are attached to membranes

Endoplasmic Reticulum

Pairs of parallel membranes extending through the cytoplasm and connecting cell membrane with nuclear membrane

\-Smooth ERs have no ribosomes attached

\-Rough ERs have ribosomes attached, this is most ERs.

\-Provides a surface where chemical reactions can occur

\-Channels between paired membranes used for the storage or transport of materials

Lysosomes

Breakdown materials taken into the cell and breakdown worn-out organelles.

\-Small spheres

\-Contain enzymes that break down lipids, proteins, nucleic acids and some carbohydrates.

Mitochondria

Releases energy through respiration of the cell

\-Spherical or elongated structures spread out in the cytoplasm.

\-have double membrane: outer one smooth, inner one folded in towards the centre

Cytoskeleton

Internal scaffolding of protein fibres within the cytoplasm

\-consist of microfilament and microtubules that give shape and assist with materials, organelles and whole cell

Golgi Body

Modifies and packages proteins in vesicles for secretion from cell.

\-Flattened membranous bags stacked on top of each other.

Vesicles

The membrane-bound sac transports materials into, out of the cell and within the cell

Nucleolus

\-Contains mostly RNA

\-DNA and nucleolus are suspended in the jelly-like nucleoplasm

Inclusions

Chemical substances occurring as granules or liquid droplets in the cytoplasm.

\-not part of the cell structure

\-e.g. haemoglobin in red blood cells, the pigment in hair, eyes and skin.

Centrioles

\-pair of cylindrical structures

\-located near the nucleus

\-involved in the reproduction of cells

Cytoplasm

Thick fluid within the cell membrane and all structures suspended in it

\-excluding nucleus

Organelles

Structures suspended in cytoplasm that carry out particular functions

Cytosol

The liquid part of the cytoplasm

\-75-90% water