Eukaryotic Cell

Cell-surface (Plasma Membrane): Description (2)

The membrane found on the surface of animal cells and just inside the cell wall of other cells

It’s made mainly of lipids and protein

Cell-surface (Plasma Membrane): Function (2)

Regulates the movement of substances into and out of the cell

It also has receptor molecules on it, which allow it to respond to chemicals like hormones

Nucleus: Description (2)

A large organelle surrounded by a nuclear envelope (double membrane) which contains many pores

The nucleus contains chromosomes (which are made from protein-bound linear DNA) called a nucleolus

Nucleus: Function (4)

Controls the cell’s activites (by controlling the transcription of DNA)

DNA contains instructions to make proteins

The pores allow susbtances to move between the nucleus and the cytoplasm

The nucleolus makes ribosomes

Mitochondrion - Structure (3)

Usually oval-shaped

They have a double membrane - the inner one is folded to form structures called cristae

Inside is the matrix, which contains enzymes involved in respiration

Mitochondrion: Function (2)

The site of aerobic respiration where ATP is produced

They’re found in large numbers in cells that are very active and require a lot of energy

Chloroplast: Description (4)

A small, flattened structure found in plant and algal cells

Its surrounded by a double membrane, and also has membranes inside called thylakoid membranes

These membranes are stacked up in some parts of the chloroplast to form grana

Grana are linked together by lamella - thin, flat pieces of thylakoid membrane

Chlorplast: Function (2)

The site of photosynthesis

Some parts of photosynthesis happen in the grana, and other parts happen in the stroma (a thick fluid found in chlorplasts)

Golgi apparatus: Description (2)

A group of fluid-filled, membrane-bound flattened sacs

Vesicles are often seen at the edges of the sacs

Golgi apparatus: Function (2)

It modifies, processes and packages new lipids and proteins

It also makes lysosomes

Golgi vesicle: Description (2)

A small fluid-filled sac in the cytoplasm, surrounded by a membrane

Produced by the Golgi apparatus

Golgi vesicle: Function (2)

Stores lipids and proteins made by the Golgi apparatus

Transports them out of the cell (via the cell-surface membrane)

Lysosome: Description (2)

A round organelle surrounded by a membrane, with no clear internal structure

It’s specialised form of a Golgi vesicle

Lysosome: Function (3)

Contains digestive enzymes called lyzozymes (hydrolytic enzymes)

These are kept seperate from the cytoplasm by the surrounding membranes

They can be used to break down pathogens ingested by phagocytes or to break down worn out components of the cell

Ribosome: Description (3)

A very small organelle that either floats free in the cytoplasm or is attached to the rough endoplasmic reticulum

It’s made up of proteins and RNA

It’s not surrounded by a membrane

Ribosome: Function

The site where proteins are made

What does each ribosome unit contain?

Ribosomal RNA and protein

What are the two types of ribosomes (2)

80s - found in eukaryotes

70s - found in prokaryotes, mitochondria and chloroplasts

Rough Endoplasmic Reticulum (RER): Description (2)

A system of membranes enclosing a fluid-filled space

The surface is covered with ribosomes

Rough Endoplasmic Reticulum (RER): Function

Folds and processes proteins that have been made at the ribosomes

Smooth Endoplasmic Reticulum (SER): Description

Similar to rough endoplasmic reticulum, but with no ribosomes

Smooth Endoplasmic Reticulum (SER): Function

Synthesises and processes lipids

Cell Wall: Description (3)

A rigid structure that surrounds cells in plants, algae and fungi

In plants and algae its made mainly of the carbohydrate cellulose

In fungi its made of chitin

Cell Wall: Function

Supports cells and prevents them from changing shape

Cell Vacuole: Description (3)

A single membrane-bound organelle found in the cytoplasm of plant cells

It contains cell sap - a weak solution of mineral salts, sugars, amino acids, wastes and some pigment

The surrounding membrane is called the tonoplast

Cell Vacuole: Function (4)

Support herbaceous plants, and herbaceous parts of woody plants, by making cells turgid

Sugars and amino acids may act as a temporary food source

Pigments may colour petals to attract pollinating insects

Also involved in the isolation of unwanted chemicals inside the cell

What is the cell wall made of?

Many polysaccharides, including cellulose

What is the middle lamela?

The thin layer which marks the boundary between adjacent cell walls and cements them together

What are the functions of the cell wall? (3)

Provides mechanical strength - prevents the cell from bursting under the pressure created by osmotic entry of water

Gives mechanical strength to the whole plant

Allows water to pass along it which contributes to water movement through the plant

What are plasmodesmata? (3)

Microscopic channels that cross the cell walls of plant cell and some algae

They link their cytoplasms

This is for direct transport and communication

What are the cell walls of fungi made of? (3)

A mixture of nitrogen-containing polysaccharide called chitin

A polysaccharide called glycan

Glycoproteins

What are algae cell walls made of? (3)

Cellulose

Glycoproteins

A mixture of both