cell components and organelles

Question 1

what is the plasma membrane?

Answer 1

• semi permeable membrane
• double phospholipid layer with proteins embedded
• glycolipids/glycoproteins are present

Question 2

what is the cytoplasm?

Answer 2

• the material outside the nucleus and inside the plasma membrane
• contains the organelles as well as the fluid called the cytosol

Question 3

what is the cytosol?

Answer 3

• the fluid that suspends other elements
• dissolved nutrients, enzymes and other molecules

Question 4

what is the mitochondria?

Answer 4

• double membrane
• inner membrane is folded
• involved in making ATP which is the cells energy source

Question 5

what are ribosomes?

Answer 5

ribosomes are cell structures that are composed of two subunits made from the RNA and protein molecules. ribosomes are the site of protein synthesis. ‘free’ ribosomes are suspended in the cytosol and produce protein molecules that are used by the cell.

Question 6

what is an endoplasmic reticulum?

Answer 6

• is an extension of the nuclear envelope, network of membranes that form hollow tubes and flattened sheets
  RER
• made of flattened sheets of membrane that studded with ribosomes. proteins that are made by the ribosomes on the rough ER pass through the membrane and enter the lumen of the rough ER
  SER
• the hollow, tube-like sections of the ER that do not contain ribosomes are called SER, the SER has a number of different functions including synthesis of lipids- including phospholipids and steroid hormones
  breakdown of carbohydrates
  detoxification of poisons and drugs
  storage of calcium ions

Question 7

what is the golgi apparatus?

Answer 7

• flattened membranous sacs
• modifies and packages protein for export out of the cell
• The Golgi apparatus receives molecules in vesicles from the ER. The Golgi apparatus modifies, stores and packages the molecules into outgoing vesicles. The vesicles travel to the right place in the cell or to the cell membrane, where they secrete their contents outside the cell.

Question 8

what are lysosomes?

Answer 8

• contains digestive enzymes
• break down foreign material and worn-out cellular parts

Question 9

what is a cytoskeleton?

Answer 9

• network of protein filaments
• proteins provide support and shape for cell
• found in prokaryotes and eukaryotes

Question 10

what are centrioles?

Answer 10

• associated with cell reproduction
• made of protein filaments
• only found in eukaryotes

Question 11

what is the nucleus?

Answer 11

• contains vital information for cellular function
• contains code for building proteins

Question 12

what is the nuclear envelope and nucleoli?

Answer 12

nuclear envelope
- double membrane barrier around nucleus
- has nuclear pores to allow material to move in both directions
nucleoli
- organelles in the nucleus where ribosomes are made
- nucleoli are made of proteins and RNA and form around specific chromosomal regions

Question 13

what are vacuoles?

Answer 13

• vacuoles are large vesicles that act as storage centres for water and many other substances
• in animal cells, vacuoles tend to be small and can be used for temporary storage of materials
• plant cells tend to have a large central vacuole that stores water and nutrients. the contents of this type of vacuole is called cell sap, vacuoles are important in plant cells as they provide structural support and waste disposal as well as storage, 80-90% of a plant cell can be occupied by a vacuole

Question 14

what are chloroplasts?

Answer 14

• a plastid containing chlorophyll and other pigments, occurring in plants and algae that carry out photosynthesis.

Question 15

what are cilia and flagella?

Answer 15

1. cilia move material across the cell surface, e.g, respiratory cells
2. flagella propels the cell, giardia