Chapter 1: Cellular Biology

Question 1

Prokaryotes include:

Answer 1

Cyanobacteria (blue-green algae), bacteria, and rickettsia

Question 2

Where does the word eukaryote come from?

Answer 2

Eu = good
Karyon = nucleus

Question 3

What defines a eukaryote?

Answer 3

a characteristic set of membrane-bound intracellular compartments called organelles that includes a well-defined nucleus

Question 4

What defines a prokaryote?

Answer 4

Contain no organelles, and their nuclear material is not encased by a nuclear membrane. They also lack a distinct nucleus.

Question 5

Describe the nuclei of prokaryotic cells.

Answer 5

Genetic information is stored in a single circular chromosome and lack histones

Question 6

Eukaryotes include:

Answer 6

Humans, animals, plants, single celled-organisms such as fungi, protozoa, and most algae

p. 2

Question 7

Describe the basics of cell differentiation

Answer 7

Some cells eventually perform one kind of function and others perform other functions

Question 8

Name the eight chief cellular functions

Answer 8

Communication
Conductivity
Excretion
Metabolic absorption
Movement 
Reproduction
Respiration
Secretion

Question 9

What are the 3 components of a “typical” eukaryotic cell? (p. 2)

Answer 9

outer membrane called the plasma membrane or plasmalemma, a fluid filling called cytoplasm, and the intracellular organelles.

Question 10

Describe the membranes surrounding the nucleus.

Answer 10

Two membranes comprise the nuclear envelope. The outer membrane is continuous with membranes of the endoplasmic reticulum. The inner membrane encloses the neoplasm.

Question 11

What is the nucleus? What is contained in the nucleolus?

Answer 11

The largest of the organelles; it contains the nucleolus. The nucleolus is a small dense structure composed largely of RNA. It contains most of the cellular DNA and the DNA-binding proteins (histones).

Question 12

What do histones do?

Why is this important?

Answer 12

Bind to DNA to cause it to fold into chromosomes.

Wrapping of DNA into tight packages of chromosomes is essential for cell division in eukaryotes.

Question 13

What is the primary function of the nucleus?

Answer 13

Cell division and control of genetic information.

Question 14

Where does most of the processing of RNA occur?

Answer 14

in the nucleolus (p. 4)

Question 15

What is the cytoplasm and the cytoplasmic matrix?

Answer 15

Cytoplasm is an aqueous solution (cytosol) that fills the cytoplasmic matrix, which is the space between the nuclear envelope and the plasma membrane.

Question 16

What fraction of the cell’s volume is represented by the cytosol?

Answer 16

about 1/2

Question 17

What is contained in the cytosol?

Answer 17

1. thousands of enzymes involved in intermediate metabolism
2. ribosomes which make proteins
3. storage for fat, carbohydrates, and secretory vesicles

Question 18

Where do newly synthesized proteins remain if they lack a signal for transport to a particular organelle?

Answer 18

In the cytosol

Question 19

Where are ribosomes synthesized and how do they get to the cytoplasm?

Answer 19

in the nucleolus; they are secreted into the cytoplasm through pores in the nuclear envelope called nuclear pore complexes (NPCs).

Question 20

What are ribosomes?

Answer 20

RNA-protein complexes (also called nucleoproteins) which synthesize proteins.

Question 21

What is the endoplasmic reticulum?

Answer 21

a membrane factory that synthesizes and transports the protein and lipid components of most of the cell’s organelles.

Question 22

What does the endoplasmic reticulum consist of?

Answer 22

a network of tubular or saclike channels called cisternae, that extend throughout the cytoplasm and are continuous with the outer nuclear membrane

Question 23

What are the two types of folded membranes within the endoplasmic reticulum?

Answer 23

rough (granular) or smooth (agranular).

Question 24

Why is the rough endoplasmic reticulum rough? (p. 6)

Answer 24

because ribosomes and ribonucleoprotein particles are attached to it

Question 25

What is the function of the Golgi complex?

Answer 25

Proteins from the ER are processed and packaged into small membrane-bound sacs called secretory vesicles, which collect at the end of the membranous folds of the Golgi bodies – called cisternae.

Question 26

Lysosomes function as…

Answer 26

the intracellular digestive system.

p. 7

Question 27

Lysosomal enzymes are capable of…

Answer 27

digesting most cellular constituents completely to their basic components

Question 28

What do lysosomes contain?

Answer 28

More than 40 digestive enzymes called hydrolases which catalyze bonds in proteins, lipids, nucleic acids, and carbohydrates.

Question 29

Why is the integrity of the lysosomal membrane so important? (p. 7)

Answer 29

It acts as a shield between the powerful digestive enzymes in the lysosome and the cytoplasm. Disruption of this membrane by various treatments or cellular injury leads to release of enzymes which can cause cellular self-digestion.

Question 30

Lysosomal storage diseases may be the result of… (p. 7)

Answer 30

…a genetic defect or lack of one or more lysosomal enzymes.

Question 31

An example of a lysosomal storage disease is Pompe disease. What causes this?

Answer 31

the lack of lysosomal alpha-1,4-glucosidase leads to an accumulation of glycogen in lysosomes. It is also called acid maltase deficiency.

Question 32

Describe the role of lysosomes in gout. (p. 7)

Answer 32

undigested uric acid accumulates within lysosomes, damaging the lysosomal membrane. Enzyme leakage occurs, resulting in cell death and tissue injury.

Question 33

What is the difference between a primary lysosome and a secondary lysosome (aka: heterophagosome)? (p. 8)

Answer 33

A primary lysosome does not maintain such an acidic internal pH. They are inactive in a sense. When a primary lysosome fuses with a vacuole or other organelle, its pH falls and the hydrolytic enzymes become activated.

Question 34

What is the term for degradation process of intracellular debris and what does this involve? (p. 8)

Answer 34

Autophagy. This process promotes homeostasis and involves continuous biosynthesis and cell turnover.

Question 35

Products of autophagy pass out of the lysosome and are ______ by the cell. Indigestible material is stored in vesicles known as ________ ______. The contents are ________ ________ from the cell.

Answer 35

reused
residual bodies
actively expelled
(p. 8)

Question 36

High concentrations of lipids may accumulate within the residual bodies and remain there for a long time. The lipids are eventually oxidized, and a pigmented substance containing polyunsaturated fatty acids and proteins accumulates in the cell. This pigmented substance termed __________, is often called “age pigment” or “age spots”, and is noted in older individuals.

Answer 36

lipofuscin

p. 8

Question 37

Peroxisomes (microbodies) are membrane-bound organelles that contain several oxidative enzymes such as ________ and _____ _______.

Answer 37

catalase
urate oxidase

(p. 8)