Cell Structure and Function - Part 2

Question 1

What are ribosomes

Answer 1

formed from rRNA; stain with hemotoxilin. They synthesize proteins. Can be free or bound to rough ER

Question 2

What happens to ribosomes that go to rough ER

Answer 2

Proteins bound for secretion; mRNA comes out and ribosome finds it and has code that it goes to rough ER.

Question 3

What is the rough ER

Answer 3

Contains ribosomes on cytoplasmic surface

• Proteins that are destined for the membrane, lysosomes, or secretion
• form cristae
• if a protein

Question 4

What is smooth ER

Answer 4

• Form tubule structures
• synthesis of lipids, and steroids
• degradation of toxic compounds
• production of HCl in stomach
• Sequesters Ca++ in muscle

Question 5

What is golgi apparatus

Answer 5

membrane bound organele
-further modifies and packages proteins made by rough ER

trans phase: package and take proteins to lysosoms, membranes, secretory vesicles, or constitutive secretion (default pathway)

Question 6

What is the pathway for protein synthesis and transport

Answer 6

1. mRNA comes from nucleus to Rough ER
2. Gets glycosylated in rough ER
3. vesicles transport proteins to cis face of golgi apparatus
4. they get further modified as they move through golgi apparatus
5. At trans face they get sorted and packaged into vesicles to travel to their final destination.

Question 7

what are lysosomes

Answer 7

vesicles containing hydrolytic enzymes synthesized in rough ER/golgi apparatus

• breakdown proteins, lipisd, nucleic acids
• very acidic

Question 8

what are peroxisomes

Answer 8

membrane bound small envmt

• oxidize fatty acids
• contain hydrogen peroxide and catalase
• use enzymatic staining

Question 9

what are non membranous organelles

Answer 9

1. ribosomes

2. all of the components of the cytoskeleton

Question 10

What is actin

Answer 10

thin filament

• involved in cell shape, movement and structural support
• form globules; G-actin: soluble monomer subnunit.
• F-actin: double stranded helical filaments; have polarity

Question 11

What are microtubles

Answer 11

largest component of cytoskeleton; Each tubule is formed from 13 protofiliaments

• Tubulin dimersS: 1 alpha and 1 beta
• Have polarity
• Dyneins move toward center of cell (+)
• Kinesins move toward periphery of cell (-)

Question 12

What are specialized structures formed by microtubuls

Answer 12

Cilia and Flagella

-Axoneme: 9 microtubule doublets around 2 central microtubules

Question 13

Each doublet is formed from an A- tubule and a B tubule. A tubule is formed from ___protofilaments. B- tubule is formed from ___ or ___protofilaments

Answer 13

13, 10 or 11

Question 14

What support microtubules

Answer 14

Centrosomes: Support
mitotic spindles and help with sequesteration of sister chromatids during mitosis
Centrioles: 9 triplets of microtubules without central microtubules; continuous with axoneme

Question 15

____filaments are another component of the cytoskeleton

Answer 15

Intermediate filaments: provide tensile strength to the cell and form keratins, vimentins, neurofilaments and lamins

• Dont have polarity
• Subunit is a long alpha helical chain formed by a dimer which form antiparralel tetramers.

Question 16

What are components of the cell cycle

Answer 16

1. G0; Restriction checkpoint: where most cells are just sitting, or stem cell thats not actively dividing. Most cells in our body
2. G1 phase: cell growth.
3. S phase: Replicates
4. G2 phase: undergoes any DNA damage repair and continues to grow
5. mitosis

Question 17

mitosis

Answer 17

1. prophase: chromosomes condense. nuclear envolope degrades
2. metaphase: microtubules form and chromosomes align on metaphase plate
3. anaphase: sister chromatids are separated toward poles
4. telophase: nuclear envolope reforms; chromosomes decondense