Lecture 1 - Cell

Define cell

Basic living structural and functional unit of the body, primarily formed from carbon, oxygen, hydrogen and nitrogen.

What are the levels of structural organisation?

- Chemical
- Cellular
- Tissue
- Organ
- Organ system

What are the three functions of cells?

1. Protection and support
2. Communication
3. Energy production
4. Movement
5. Inheritance
6. Transport

Describe the three main organised components of the cell

1. Plasma membrane
2. Cytoplasm
3. Nucleus

Define what the function of plasma membrane is

A flexible film that surrounds all cells, forming a barrier between intracellular fluid and extracellular fluid

Describe the structural framework of the plasma membrane

Lipid bilayer - two layers of phospholipids with a embedded cholesterol, glycolipids & integral proteins

What is the difference between passive and active membrane transport?

- Passive membrane transport - a molecule moves down its concentration gradient across the membrane using its own kinetic energy of motion
- Active membrane transport - ATP used to drive the substance against its concentration gradient

Define simple diffusion

Net movement of molecules from a region of higher to lower concentration

Define facilitated diffusion

Net movement of molecules from a region of higher to lower concentration via ion channels or carrier proteins

Define osmosis

Net movement of water through a selectively permeable membrane from a high concentration of water to a low concentration of water

Define isotonic solution and its osmotic effect

Same total solute and water concentration as the cells
No osmotic effect

Define hypertonic solution

Where there is more solute and less water in cells
Cell shrinkage

Define hypotonic solution

Where there is less solute and more water in the cell
Cell-lysis

Define active transport

uses cellular energy to drive the movement of solutes against electrochemical gradients across plasma membrane

Name and explain the three types of active transport

- Primary active transport
Direct ATP use
- Secondary active transport
Downward gradient of another solute used to power uphill transport
- Bulk transport
Where ATP is required to move larger packets of substances into and out of the cell
> Exocytosis - ejection of substances - vesicles merge with the plasma membrane to move material out of a cell
> Endocytosis - vesicles detach from the plasma membrane to move materials into a cell

Define cytoplasm

All the cellular contents within the plasma membrane except the nucleus

What is cytosol?

- Fluid portion of the cytoplasm > contains 75-90% water as solvent with dissolved nutrients, ions, proteins and waste products
- Has a high concentration of K+ ions and suspended proteins in comparison to extracellular fluid
- Site of many chemical reactions that maintain cell structures
- Allows for cellular growth

Define cell organelle

Specialised structures suspended within the cytosol that perform specific functions within the cell

Name three membrane bounded organelles

- Mitochondria
- Endoplasmic Reticulum
- Golgi Apparatus
- Lysosomes
- Peroxisomes
- Ribosomes
- Centrioles
- Proteasomes

Define and state the function of the cytoskeleton

- Proteins organised in fine filaments or slender tubes extending throughout the cytosol
- Provides cell strength + supports the organelle + permits movement of cellular structures + determines cell shape

Define centrosome

Region near the nucleus from which microtubules form
Contains a pair of centrioles at right angles

Define centrioles

Rod shaped bodies that are made up of fine microtubules

Define and state the function of cilia

- Short hair like projections from the cell surface
- Moves materials and fluids over cell surface

Define and state the function of flagella

- Longer than cilia and constitutes the sperm cell's tail
- Moves the entire cell directionally

Define and state the function of microvilli

- Membrane extensions
- Increase cell surface area to facilitate absorption of extracellular solute

Define and state the function of ribosomes

- Structures made up of RNA and proteins
- Site of protein synthesis

Define and state the function of endoplasmic reticulum

- Network of membranous flattened sacs or tubules
> Rough ER - has ribosomes bound to the membranes that store, transport and package newly synthesised proteins
> Smooth ER - lack attached ribosomes that aid in the synthesis of lipids and steroids + detoxification of drugs

Define and state the function of Golgi Apparatus

- Flattened membranes called cisternae
- Storage, further modification and sorting/packaging of proteins, secretory products and lysosomal enzymes

Define and state the function of lysosomes

- Vesicles that bud off from Golgi complex, containing powerful digestive enzymes
- Intracellular removal of worn out organelles and pathogens

Define and state the function of peroxisomes

- Smaller than lysosomes but similar
- Undertake oxidation of amino acids and fatty acids and neutralisation of toxic compounds

Define and state the function proteasomes

- Protein complexes
- Degrade damaged proteins by proteolysis

Define and state the function of mitochondria

- comprise of mitochondrial cristae and have the mitochondrial matrix enclosing important metabolic enzymes
- produces ATP

Define and state the function of nucleus

- Consists of a double nuclear envelope, nuclear pore and nucleolus
- Serves as control centre for cellular operations
> Nuclear pores - Control the movement of substances between nucleus and cytoplasm
> Nucleolus - Produces ribosomes and the gens arranged on chromosomes

Define tissue and name the four basic types

- Group of cells that functions together to perform one or more specialised activities
- Epithelial, connective, muscular and nervous

What are the general features of epithelial tissue?

- Cells are arranged in sheets and densely packed
- Cells are supported by a basement membranes
- Epithelial tissue is avascular but has a nerve supply

What are the three functions of epithelial tissue?

1. Absorption (small intestine)
2. Secretion and Excretion
3. Solute transport (kidney tubules)
4. Protection (skin)
5. Sensory reception (taste buds)

What are the general features of connective tissue?

1. Most abundant tissue
2. Contains cells and extracellular matrix

What are the general features of muscular tissue?

- Consists of fibres that provide motion, maintain posture and produce heat
- 3 types - skeletal, cardiac and smooth

What are the two types of nervous tissue? Describe the functions

- Two types of cells - neurons and neuroglia
- Neurons provide the ability of sensing, thinking, remembering, controlling muscle activity, and regulating glandular secretions.
- Neuroglia support, feed, and protect neurons, and maintain the interstitial fluid that bathes them.