Cells Flashcards
What research resulted in cell theory?
In 1665 Robert Hooke looked at slices of cork under a microscope and discovered compartments he named cells
Identify the elements of cell theory
All cells are made from pre-existing cells
All known living things are made up of one or more cells
The activity of an organism depends on the total activity of independent cells
Energy flow occurs within cells
Cells contain DNA & RNA
All cells are basically the same in chemical composition in organisms of similar species
List the basic components of a eurkaryotic cell
Complex structure
DNA contained in the nucleus
Single or multi-celled organisms
Includes animals, plants, fungi etc.
Describe the basic structure of a eurkaryotic cell
Cell membrane encases cell contents including
cytoplasm, organelles cytosol and the nucleus which contains DNA
Define organelles
‘Little organs’ are structures within a cell that perform cellular tasks. They are either nonmembranous or membranous
List nonmembranous organelles
Cytoskeleton Microvilli Centrioles Cilia Ribosomes
List membranous organelles
Mitochondria Endoplasmic Reticulum Golgi Complex Lysosomes Peroxisomes
What are the differences between membranous and nonmembranous organelles?
Nonmembranous: Are not covered by a membrane and are in direct contact with cytosol
Membranous: Are separated from cytosol by membrane
What three components make up the cytoskeleton?
Mircofilaments
Intermediate filaments
Microtubules
List two components of microfilaments
- Contain actin and myosin
- Possess contractile ability
What do intermediate filaments do?
Stabilise cell and cell components
List two components of microtubules
- Determining cell shape
- They are involved in movement
Describe microvilli
Small finger-like projections that increase the surface area of cell and line the areas of the digestive tract
Describe cilia
Long finger-like extensions of cells that line the respiratory tract, can beat in rhythm and move mucus to the throat for swallowing
Describe centrioles
Short sections of microtubules surrounded by centrosome and form spindle structures during cell division
Where are ribosomes found?
Ribosomes are either dispersed freely in cytoplasm or fixed on rough endoplasmic reticulum, they are also found in the mitochondria
What do ribosomes do?
Synthesise proteins
Describe mitochondria
They are the sites of energy production, thought to originate from bacteria, contain their own DNA and produce the majority of ATP
Describe endoplasmic reticulum
Membrane network of flattened sacs and tubules attached to the nuclear envelope
Describe rough endoplasmic reticulum
It is continuous with the nuclear membrane with ribosomes on the surface and are involved in the manufacture of proteins
Describe smooth endoplasmic reticulum
It extends from rough endoplasmic reticulum and synthesise fatty acids and steroids
What processes are the enzymes of smooth endoplasmic reticulum involved in?
- Inactivation and detoxification of drugs, alcohol, pesticides and carcinogens
- Breakdown of glycogen to glucose in the liver
What is the function of the golgi complex?
It modifies, sorts and packages proteins and lipids
What is the golgi complex?
A flattened collection of sacs called cisternae
What is the function of lysosomes?
They are involved in garbage disposal and recycling, fusing with vesicles containing damaged organelles and bacteria. They break down the contents and eject unwanted components from the cell
What are peroxisomes?
Small vesicles containing powerful oxidising enzymes that detoxify harmful substances such as alcohol. pH of which is 5-100x more acidic than cytosol
Where are peroxisomes most prevalent?
Liver cells
