Chapter 3 - Cells

Question 1

What is cell theory?

Answer 1

• Cells are the building blocks of all organisms
• All cells come from the division of preexisting cells
• Cells are the smallest anatomical units that perform all vital physiological functions
• Cells contain hereditary information

Question 2

What is the basic structure of the cell?

Answer 2

1. Plasma membrane
2. Cytoplasma containing organelles
3. Nucleus

Question 3

What is the Plasma Membrane? What is it made of?

Answer 3

The plasma membrane forms the outer boundary of the cell, it’s semipermeable that allows some substances to enter and leave the cell.

• About 50% lipids
• About 50% proteins
• About 5% carbohydrates

Question 4

What is the phospholipid bilayer? What are they made of?

Answer 4

Phospholipids are plasma membrane lipids that are made up of hydrophilic heads (polar) and hydrophobic fatty acid tails (non-polar)

Question 5

What is the cholesterol?

Answer 5

It is a plasma membrane lipid that is interspersed among the phospholipids and provides stability to the plasma membrane

Question 6

What are some plasma membrane proteins?

Answer 6

Integral, peripheral, transport, receptor,

Question 7

What are the different types of transport proteins?

Answer 7

Channels proteins, carrier proteins, and ATP-powered pumps

Question 8

What is the cytoplasm? What are the components?

Answer 8

All material inside the cell, but outside of the nucleus

• Cytosol
• Cytoskeleton
• Organelles

Question 9

What is the Cytosol?

Answer 9

Fluid portion of the cytoplasm that surrounds the organelles.

Question 10

What is the cytoskeleton? What are the 3 groups of proteins that make up the cytoskeleton?

Answer 10

The cytoskeleton is a network of protein filaments that extends throughout the cytosol. It supports the cell.

• Microtubules
• Microfilaments
• Intermediate filaments

Question 11

What are microtubules made of and their function?

Answer 11

Made of tubulin protein. Transport, cell divison.

Question 12

What are microfilaments made of and their function?

Answer 12

Made of actin protein. Structure & support

Question 13

What is the function of intermediate filaments?

Answer 13

Shape and rigidity of the cell.

Question 14

What are microvilli?

Answer 14

• Increase surface area for absorption
• Attached to the cytoskeleton

Question 15

What are centrioles?

Answer 15

• Located near the nucleus
• Form spindle apparatus during cell divison

Question 16

What are cilia?

Answer 16

• Slender extensions of plasma membrane
• Move fluids across the cell surface (requires ATP)

Question 17

What are flagella?

Answer 17

A whip-like tail that is used to propel the cell through a fluid environment. (only found in sperm cells)

Question 18

What are ribosomes? What are the two types? Define them.

Answer 18

Ribosomes are organelles that synthesize (make) proteins—composed of large and small subunits. It also contains ribosomal RNA (rRNA).

Free ribosomes:
- In cytoplasm
- Make proteins that stay inside the cell

Membrane-bound ribosomes:
- Attached to the ER
- Make proteins that stay outside the cell

Question 19

What is the Endoplasmic Reticulum (ER)? What are the two types? Define them.

Answer 19

The ER contains storage chambers known as cisternae. It’s involved in the synthesis, storage, and transport of various substances.

Smooth ER: No ribosomes, synthesizes lipids
Rough ER: Covered with ribosomes, active in protein synthesis & encloses products in transport vesicles.

Question 20

What is the function of the Golgi apparatus?

Answer 20

• Modifies and packages secretions
• Renews or modifies plasma membrane
• Packages special enzymes within vesicles

Question 21

What is a Lysosome?

Answer 21

A specialized type of vesicle formed by the Golgi. It destroys bacteria, breaks down molecules, and recycles damaged organelles.

Question 22

What is the Mitochondria? What are the different parts?

Answer 22

It’s the smooth outer membrane that provides energy for the cell.

Cristae: Inner membrane folds
Matrix: Fluid contents

Question 23

What is the Nucleus? What are the different parts?

Answer 23

The nucleus controls and regulates the activities of the cell and carries the genes, and structures that contain the hereditary information (DNA).

• Nuclear envelope
• Nuclear pores
• Inner and outer membranes

Question 24

What is Diffusion?

Answer 24

Net movement of a substance from area of higher concentration to area of lower concentration.

Question 25

What is Osmosis?

Answer 25

- Diffusion of water across a selectively permeable membrane - Water molecules move from a low to a high concentration

Question 26

What is meant by Osmolarity (osmotic concentration) and Tonicity?

Answer 26

Osmolarity: The total solute concentration in a solution. Tonicity: describes how a solution affects cells.

Question 27

What are the three different types of solutions? Define them.

Answer 27

- Isotonic solution (cell will stay the same size and shape) * Does not cause osmotic flow - Hypotonic solution (cell will get bigger) * Lower solute concentration than the cell - Hypertonic solution (cell will shrink) * Higher solute concentration than the cell

Question 28

What are the two ways that diffusion can occur?

Answer 28

1. Lipid bilayer 2. Membrane Channels

Question 29

What are some factors that can affect diffusion rates? Describe them.

Answer 29

- Concentration Gradient: * Greater difference, greater rate of diffusion - Temperature of the solution * Higher temperature, higher rate of diffusion - Size of the diffusing molecules * Smaller the molecule, higher rate of diffusion

Question 30

What is Mediated Transport? What are the 3 different types?

Answer 30

Moves large, water-soluble molecules, electrically charged molecules, or ions across the plasma membrane - Facilitated Diffusion - Active Transport - Secondary Active Transport

Question 31

What are the characteristics of mediated transport? Explain each.

Answer 31

1. Specificity: Each transport protein binds to and transports only a single type of molecule 2. Competition: Similar molecules binding to the same. transport protein. 3. Saturation: Rate of movement of molecules across the PM is dependent on the number of available protein transporters.

Question 32

What is facilitated diffusion?

Answer 32

* Carrier mediated or channel mediated diffusion from a higher solute concentration to lower solute concentration * No energy required (Passive) * Is dependent on concentration gradient

Question 33

What is active transport?

Answer 33

- Movement of substance to opposite side of PM and release from the pump REQUIRES energy * Rate depends on availability of pumps and ATP * Can move substances with OR against their concentration gradient

Question 34

What is secondary active transport?

Answer 34

* The movement of one ion down its concentration gradient provides the energy to allow a second molecule to move against its concentration gradient.

Question 35

What is Endocytosis?

Answer 35

When ATP is used to engulf substances by vesicle formation

Question 36

What is Exocytosis?

Answer 36

When ATP is used to release substances from a secretory vesicle to the outside of the cell.