Module 1 Biology - Cells and the basis of life

magnification 

The process of making something look bigger than it is.  

resolution

The ability to distinguish between two closely spaced objects as separate entities rather than a single, blurry point. 

prokaryotic

single-celled organisms, like bacteria and archaea, that lack a membrane-bound nucleus and internal organelles 

eukaryotic 

relating to a cell containing a membrane-bound nucleus and membrane-bound organelles.  

unicellular

an organism composed of a single cell, which independently  performs all life functions eg metabolism, reproduction, nutrition, and excretion.  

Cell

refers to the smallest structural and functional unit of a living organism 

 

Organelle

membrane bound compartments within the cell.  

Each organelle does a different job function) that helps keep the cell alive 

Nucleus

• Contains the cell's genetic information -> chromosomes > contains dna  

• Needed for growth, repair and proper functioning  

• It contains an organelle called the nucleolus: found in the nucleus, mainly made of proteins and ribonucleic acid (RNA), where ribosomes are made 

Ribosomes

made out of ribosomal RNA and protein 

• They make proteins  

• They are connected to the endoplasmic reticulum  

Endoplasmic reticulum ER 

Connected to the nucleus in certain places 

Its a network of flattened, interconnected membranes creates a "tunnel" through which substances can move 

Rough ER

has ribosomes) - proteins made, process and modify proteins

Smooth ER

NO ribosomes) - make lipids (fats)  

Golgi body

made of flat membrane sacs stacked on top of each other 

Job process and packages substances the cell has made  

Eg. Proteins made in the rough ER may be sent here, after processing, the membrane pinches off around the substance to form a VESICLE

Vesicle

made by the golgi body to transport substances to whereever they are needed, inside or outside of cell

Lysosomes

A specific example of a package (vesicle) made by the Golgi body  

Membrane bound sacs that contain digestive enzymes -> needed to break down other substances like waste or foreign particles. 

Chloroplasts

• Only found in plants  

• Disk shaped which have a double membrane, their own DNA and chlorophyll 

• Capture light energy (sun) and use it to perform photosynthesis (which creates glucose) --> mitochondria 

 

Mitochondria

• Have double membrane (inner membrane is highly folded) and own DNA  

• Perform chemical respiration: combine oxygen with glucose = ATP (energy)  

• Number of mitochondria in a cell depends on how much energy the type of cell needs 

Cell membrane

• Job seperates cell contents from the outside environment, hold organelles together and protects them 

• Semi-permeble, regulates the movement of substances into and out of the cell 

Cell wall

 external structure that surrounds the cell membrane  

It gives cell structural strength and protection  

Cytoplasm

• Watery, gel-like fluid inside the cell membrane 

• All organelles are suspended in the cytoplasm  

• Fills up the cell'svolum and gives it shape 

 

Cystoskeleton:  

Held by a network of, micortubles, microfilamentsm intermediate filaments  

• Protein spider web  

• Responable for holding the organelles in place 

 

Centrioles

• A pair of small, cylindrical structures which are made of microtubules (all wound up together)  

• involved in cell division: they pull chromosomes apart 

 

Pili and flagella

• Hair like appendages made of microtubules, and are enclosed by the cell membrane ('external') extension of the cell membrane 

• Used to help the cell move around  

Vacuole

Package that contains fluid: water, sugar, salt  

Main job: store substances for when the cell wants to use it  

Found in most cells, but size and quantity vary 

Plants --. Turgor pressure, water pushes out against the cell wall to maintain the cell's shape 

 

What is the cell membrane made of?

Two layers of phospholipid molecules to form a phospholipid bilayer. (phosphate aka hydrophilic head and 2 lipid tails aka hydrophobic)

Function of the cell membrane

To separate, regulate and communicate

What does it mean to ‘seperate’ in terms of the cell membrane

The cell membrane separates the contents of the cell from the external environment.

eg. cytoplasm is the intracellular fluid, extracellular fluid is a water like environment outside the cell.

What does it mean to ‘regulate’ in terms of the cell membrane?

The cell membrane controls which substances pass through it, so it regulates the cell’s contents.

• It is semi permeable

• it allows certain molecules to pass through it via passive or active transport.

What is the fluid mosaic model?

It is used to explain the structure and function of all cell membranes, as it behaves dynamic, flexible filled as it is constantly moving or changing shape.

mosaic - it is embedded with a collection of proteins, cholesterol and carbohydrates.