Module 3: Cells

Question 1

What is a cell?

Answer 1

The smallest structural unit of all living organisms that is capable of functioning independently.

Question 2

What are the 3 main parts the cell is divided into?

Answer 2

The plasma membrane, the cytoplasm, and the nucleus

Question 3

Describe the structure of the plasma membrane?

Answer 3

Surrounds and contains the cytoplasm of a cell. Consists mostly of phospholipids, arranged in a bilayer and proteins most of which are glycoproteins.

Question 4

Describe the structure of the cytoplasm?

Answer 4

Includes all the cellular contents between the plasma membrane and nucleus. Cytosol and organelles

Question 5

Describe the structure of the nucleus?

Answer 5

Consists of a double nuclear envelope; nuclear pores, which control the movement of substances between the nucleus and cytoplasm, nucleoli, which produces ribosomes; and genes arranged on chromosomes.

Question 6

What are the functions of the plasma membrane?

Answer 6

Acts as a barrier separating inside and outside of the cell. Controls the flow of substances into and out of the cell. Helps identify the cell to other cells (immune cells). Participates in intercellular signaling.

Question 7

Describe simple diffusion: lipid-soluble molecules diffuse through the lipid bilayer.

Answer 7

In simple diffusion there is a net (greater) movement of substances from a region of their high concentration to a region of their lower concentration.

Question 8

Describe facilitated diffusion

Answer 8

An integral membrane protein assists a specific substance to move across the membrane. The membrane protein can either form channels or function as carriers.

Question 9

What is osmosis?

Answer 9

Osmosis is the net movement of water molecules through a selectively permeable membrane.

Question 10

What is an isotonic solution?

Answer 10

One which cells maintain their normal shape and volume.

Question 11

What happens in a hypotonic solution?

Answer 11

Molecules enter the cells by osmosis faster than they leave which causes the cells to swell and eventually burst which is called hemolysis.

Question 12

What happens in a hypertonic solution?

Answer 12

Water molecules move out of the cells by osmosis faster than they enter causing the cells to shrink and shrivel up. This is called crenation.

Question 13

Explain the function of the sodium potassium pump

Answer 13

Na+ ions are expelled from the cell and K+ ions are imported into the cell. The pump does not work unless Na+ and ATP are present in the cytosol and K+ Is present in the extracellular fluid. The sodium potassium pump maintains a low intracellular concentration of Na+

Question 14

___ is a vital defense mechanism that helps protect the body from disease.

Answer 14

Phagocytosis

Question 15

Movement of substances down a concentration gradient until equilibrium is reached; do not require cellular energy in the form of ATP is __ __

Answer 15

Passive processes

Question 16

Movement of a substance by kinetic energy down a concentration gradient until equilibrium is reached is ___

Answer 16

Diffusion

Question 17

Passive movement of a substance through the lipid bilayer of the plasma membrane is __ __

Answer 17

Simple diffusion
Ex: lipid soluble molecules oxygen, carbon dioxide, nitrogenous gases, fatty acids, steroids, fat-soluble vitamins A D E K, polar molecules like water and urea

Question 18

Passive movement of a substance down its concentration gradient aided by ion channels and carriers is __ __

Answer 18

Facilitated diffusion

Ex: K+, Cl-, Na+, Ca2+, glucose, fructose, galactose and some vitamins

Question 19

Movement of water molecules across a selectively permeable membrane from an area of higher concentration to an area of lower water concentration is ___

Answer 19

Osmosis

Question 20

Movement of substances against a concentration gradient; requires cellular energy in the form of ATP is __ ___

Answer 20

Active processes

Question 21

Transport in which a cell expends energy to move a substance across the membrane against its concentration gradient aided by membrane proteins that act as pumps; these integral membrane proteins use energy supplies by ATP ___ ___

Answer 21

Active transport

Ex: Na+, K+, Ca2+, H+, I-, Cl- AND other ions

Question 22

Movement of substances into or out of a cell in vesicles that bud from the plasma membrane; requires energy supplies by ATP are __ __

Answer 22

Transport vesicles

Question 23

Movement of substances into a cell in vesicles ___

Answer 23

Endocytosis

Question 24

Cell eating; movement of a solid particle into a cell after pseudopods engulf it.

Answer 24

Phagocytosis

Ex: bacteria, viruses, and aged or dead cells

Question 25

Cell drinking; movement of extracellular fluid into a cell by infolding of plasma membrane.

Answer 25

Bulk-phase endocytosis (pinocytosis) | Ex: solutes in extracellular fluid

Question 26

Movement of substances out of a cell in secretory vesicles that fuse with the plasma membrane and release their contents into the extracellular fluid.

Answer 26

Exocytosis | Ex: neurotransmitters, hormones, and digestive enzymes

Question 27

Describe the structure of the cytoskeleton?

Answer 27

Extending throughout the cytosol, the cytoskeleton is a network of three kinds of protein filaments: microfilaments, intermediate filaments and microtubules.

Question 28

Describe the functions of the cytoskeleton.

Answer 28

Serves as a scaffold that helps to determine a cells shape and to organize the cellular contents. Aids movement of organelles within the cell of chromosomes during cell division, and of whole cells such as phagocytes.

Question 29

What is the centrosome?

Answer 29

The pericentriolar material of a centrosome organizes the mitotic spindle during cell division.

Question 30

Describe the functions of the centrosomes.

Answer 30

The pericentriolar matrix of the centrosome contains tubulins that build microtubules in non dividing cells and form the mitotic spindle during cell division.

Question 31

What are ribosomes?

Answer 31

The sites of protein synthesis, consist of a large subunit and a small subunit.

Question 32

Describe the functions of ribosomes.

Answer 32

Ribosomes associated with endoplasmic reticulum synthesize proteins destined for insertion in the plasma membrane or secretion from the cell. Free ribosomes synthesize proteins used in the cytosol.

Question 33

Describe the structure of the endoplasmic reticulum (ER)?

Answer 33

The ER is a network of folded membranes that extend throughout the cytoplasm and connect to the nuclear envelope.

Question 34

Describe the functions of the endoplasmic reticulum (ER).

Answer 34

Rough ER synthesize glycoproteins and phospholipids that are transferred into cellular organelles, inserted into the plasma membrane, or secreted during exocytosis. Smooth ER synthesis fatty acids, steroids, such as estrogens and testosterone; inactivates or detoxifies drugs and other potentially harmful substances; removes the phosphate group from glucose 6 phosphate; and stored and releases calcium ions that trigger contraction in muscle cells.

Question 35

What is the Golgi complex?

Answer 35

"A processing plant". Most proteins synthesized by ribosomes attached to rough ER pass through the Golgi complex for processing.

Question 36

What are the functions of the Golgi complex?

Answer 36

Modifies, sorts, packages, and transports proteins received from the rough ER. Forms secretory vesicles that discharge processed proteins via exocytosis into extracellular fluid; forms membrane vesicles that ferry new molecules to other organelles such as lysosomes.

Question 37

What is the 7e7374473737373mitochondrion?

Answer 37

Within mitochondria, chemical reactions generate most of a cells ATP.777e77e7e

Question 38

What is the function of mitochondria?

Answer 38

Generate ATP through reactions of aerobic cellular respiration. Within mitochondria, chemical reactions generate most of a cells ATP.

Question 39

What is the nucleus?

Answer 39

The nucleus contains most of a cells genes, which are located on chromosomes.

Question 40

Where does transcription and translation take place?

Answer 40

Transcription occurs in the nucleus; translation takes place in the cytoplasm.

Question 41

Describe messenger RNA (mRNA).

Answer 41

Directs synthesis of a protein.

Question 42

Describe ribosomal RNA (rRNA).

Answer 42

Joins with ribosomal proteins to make ribosomes.

Question 43

Describe transfer RNA (tRNA).

Answer 43

Binds to an amino acid and holds it in place on a ribosome until it is incorporated into a protein during translation. Each of more than 20 different types of tRNA binds to only one of the 20 different amino acids.

Question 44

What happens in transcription in the nucleus?

Answer 44

During transcription, the genetic information is copied to RNA.

Question 45

Describe protein elongation and termination of protein synthesis during translation in the cytoplasm.

Answer 45

During protein synthesis the ribosomal subunits join, but they separate when the process is complete.

Question 46

What are the 4 phases of cellular division?

Answer 46

Prophase, metaphase, anaphase, telophase.

Question 47

What is reproductive cell division (meiosis)?

Answer 47

The process that produces gametes - sperm and oocytes.

Question 48

What is somatic cell division?

Answer 48

A single cell divides to produce 2 identical cells.