Cells Flashcards
Defintion of eukaryotic cells
Have a distinct nucleus and membrane-bound organelles.
Describe the structure of the cell-surface membrane
7mm thick
Plasma membrane
Describe the function of the cell-surface membrane
Partially permeable membrane which controls exchange between the cell and its environment.
Describe the structure of the nucleus
Surrounded by 2 membranes known as the nuclear envelope. The envelope has nucelar pores. The nucelus contains a darker staining area, the nucleolus.
Describe the function of the nucleus
Contains genetic material as DNA and chromosomes. Produces mRNA and tRNA. The nucleolus manufactures rRNA. Nuclear pores allow mRNA and robosomes to leave the nucelus and nutrients and hormones to enter the nucleus.
Describe the structure of the mitochondria
Surrounded by 2 membranes called an envelope. 1-10 micrometers in length. The linear membrane is folded to form cristae which projects into the matrix. The matrix contains proteins, lipids, ribosomes and DNA so can producse own proteins.
Describe the function of the mitochondria
Aerobic respiration
Makes ATP
Describe the structure of rough and smooth endoplasmic reticulum
Ribosomes can be attached to the membranes = rough endoplasmic reticulum. No ribosomes = smooth endoplasmic reticulum.
Describe the function of smooth and rough endoplasmic reticulum
Rough- Provides a larger surface area for the synthesis of proteins and glycoproteins, and then transport these proteins through the cell. It makes the Golgi apparatus.
Smooth- Synthesises, stores and transports lipids and carbohydrates.
Describe the structure of the cell wall
Rigid cell wall made of polysaccharides, such as cellulose embedded in a matrix. The middle lamella is a thin layer marking the boundary between adjacent cell walls and cements cells together. Algae cell walls are made up of cellulose or glycoproteins or a mixture. In fungi, they are made of chitin.
Describe the function of a cell wall
Provides mechanical strength to the cell. Prevents the cell from bursting when water enters by osmosis. Freely permeable.
Describe the structure of a vacuole
Surrounded by a membrane called a tonoplast. Vacuole is fluid-filled.
Describe the function of a vacuole
Tonoplast controls the exchange of materials between the vacuole and the cytoplasm. Makes cells turgid for support.
Describe the structure of a chloroplast
Surrounded by 2 layers of membrane-envelope. Around 2-10 micrometers long. Stroma: a jelly-like substance inside. Membranes forming falttened sacs called thylakoid membranes = grana. Small starch grains and lipid droplets are present in the stroma.
Definition of ultrastructure
The detail of the inside of the cells, as revealed by the electron micrscope.
Definition of eukaryotes
These cells have a distinct nucelus and membrane-bound organelles.
Definition of division of labour
Each type of organelle has a specific role within the cell.
Describe the process of division of labour
- DNA in nucleus contains instructions to make proteins.
- Protein synthesised on ribosome.
- Protein transported through RER.
- Protein molecules are pinched off in vesicles and are transported towards the Golgi apparatus.
- Vesicles fuses with Golgi apparatus.
- Golgi apparatus process and packages protein molecules ready for release.
- Packaged protein molecules are pinched off in vesicles from the Golgi apparatus and are transported towards the plasma membrane.
- Vesicles fuses with plasma membarne.
- Protein leave by exocytosis.
Definition of a cell
The basic unit of living things
Definition of tissue
A group of similar or different cells work together for a specific function.
Definition of organ
Different tissues work together for a specific function