Lecture 5-7

Question 1

compartmentalization

Answer 1

• the physical separation of cell functions.
• Allows different chemical environments to exist within the cell
• Spatial arrangement of enzymes (important); allows enzymes that are required for particular metabolic pathways to be located close to one another.
  Two examples: pH; allows enzymes to function efficiently.
  Ionic gradients; generation of ATP in mitochondria

Question 2

5 Organelle functions

Answer 2

1) Information storage, processing, and execution — nucleus
2) Protein, carbohydrate, and lipid biosynthesis — endomembrane system
3) Energy storage — lipid & polysaccharide granules (glycogen, starch)
4) Energy metabolism — chloroplast & mitochondrion
5) Structural and transport functions — cytoskeleton, plasma membrane

Question 3

Chromatin

Answer 3

Chromatin Consists of DNA and its associated proteins that form cording that wraps around histones (that are structural proteins are closely associated with DNA.) Also many regulatory proteins that have many functions in controlling gene expression.

Question 4

cisternae

Answer 4

The ER is folded into a series of tubules (cisternae).

Question 5

Glycoproteins and the ER

Answer 5

Polypeptides in the ER’s cisternal space can be further modified to change their folding, and/or have carbohydrate groups added (Glycoproteins) to begin the process of protein maturation.

Question 6

Ribosomes are found in ….

Answer 6

• Free in the cytoplasm. These synthesize cytoplasmic soluble proteins,
• Bound to the endoplasmic reticulum.
• Mitochondria and Chloroplasts

Question 7

Smooth ER

Answer 7

• The SER of liver cells is the site for the synthesis and hydrolysis of glycogen.
• SER of the liver is the site for detoxification
• site of phospholipid synthesis, cholesterol and steroid synthesis.
• SER is an important reservoir for Ca2+

Question 8

Golgi Apparatus Structure

Answer 8

• there is a definite direction or polarity to the structure because of its cis/trans faces
• Similar in structure to the SER, and seen as a series of stacked discs or sacs (cisternae) within the cell.

Question 9

2 products of Golgi A.

Answer 9

proteins can be used by the cell or secreted
1. lysosomes
2. secretory vesicles

Question 10

where do newly synthesized proteins go?

Answer 10

1) secreted outside of the cell
2) inserted into the cell membrane
3) remain in the cytoplasm as soluble proteins
4) They are used to maintain organelle function, either as part of an organelle’s structure (eg. in its membrane), or inside the organelle

Question 11

Lysosomes

Answer 11

• Contains enzymes important for the digestion of all the major types of macromolecules. Have an acidic environment (pH 5) that helps the activity of these enzymes.
• autophagy = recycling cell parts “garbage disposal”
• phagocytosis = digest food particles that are brought into the cell

Question 12

mitochondria structure

Answer 12

• double membrane folded into a series of convolutions called cristae
• The rest of a mitochondrion is made up of the matrix that contains many of the enzymes
• free ribosomes in matrix

Question 13

Chloroplast Structure

Answer 13

• Structure is similar to a mitochondrion in that chloroplasts have a double membrane and a matrix, in this case called the stroma.
• However, instead of cristae, chloroplasts have a series of discs - thylakoids, which in some cases are stacked into structures called grana. The thylakoids are where chlorophyll is located and is the site of photosynthesis.

Question 14

Cytoskeleton Functions

Answer 14

• cell shape, support and anchor points for organelles
• Provides the mechanisms for cell (flagellae and pseudopodia) and organism movement (eg. muscle contraction).
• Provides tracks for motor proteins that move materials and organelles within cells.
• 3 main types: microfilaments (actin), intermediate filaments (keratin), microtubules

Question 15

Centrosomes

Answer 15

• made of microtubules
• important for cell division