Cell Biology Exam 1 (Chapter 1-5)

What statements accurately characterizes cells?

1) Cells are highly complexed and organized.

2) Cells possess a genetic program and the means to use it.

3) Cells are capable of producing more of themselves.

4) Cells acquire and utilizes energy

The genetic material of a prokaryotic cell is present in the __?

Nucleoid region

What is defined as having a poorly defined region of the cell that lacks a boundary membrane to separate it from the surrounding cytoplasm?

Nucleiod

Some bacteria can pass through a piece of DNA from a donor bacterial cell to a recipient bacterial cell through a structure called a pilus. What is this process called?

Conjugation

You are conducting an experiment by trying to reproduce the work performed in 1891 by Hans Driesch, a German embryologist. Working with a fertilized sea urchin egg, you allow it to complete the first cell division after fertilization. You then carefully separate the two cells of the embryo and allow their development to continue. Based on Driesch's experiment, which result would you expect to happen?

Both of the cells will develop into complete and normal embryos

What factor or factors discovered with electron microscopy distinguished prokaryotic from eukaryotic cells?

Size; internal structures or organelles

What is a feature NOT shared by all cells?

division of cells into nucleus and cytoplasm

Which organelle is found in both eukaryotes and prokaryotes?

ribosome

What cell types does NOT possess membrane-bound organelles?

Prokaryotic cells

Which of these cell types does NOT possess membrane-bound organelles?

E. coli

What statements about viruses is NOT true?

All viruses are obligatory intercellular parasites

What is NOT typically a behavior exhibited by a cell with a proviral infection?

Immediate production of new viruses and subsequent lysis of the host cell

What factor or factors discovered with electron microscopy distinguished prokaryotic from eukaryotic cells?

• a. their size

• b. their shape

• c. the types of their internal structures or organelles

Which of the following description of adult stem cells is wrong.

They can differentiate into every type of cell in the body

What is NOT a function of membranes?

energy transduction & protein degradation

Gorter and Grendel extracted lipids from human red blood cells. They calculated the total surface area for these red blood cell lipids and found it to be 36 um2. How much surface area would these lipids cover once they were spread across the surface of water?

72 µm²

What kind of membrane protein is found entirely outside the bilayer on either the extracellular or cytoplasmic surface and is covalently linked to a membrane lipid situated within the bilayer?

lipid-anchored protein

What characterizes the amino acids that are found in an a-helical segment that spans a membrane?

predominantly hydrophobic

Which of the following is an observed function of integral membrane proteins?

all (or just pick one)

While culturing some cells, you lower the temperature of the culture. What happens immediately to the membrane fluidity?

The membrane becomes less fluid

Which of the following cell processes depend on the movement of membrane components and would probably not be possible if membranes were rigid, nonfluid structures?

all of these are correct

Which substances will cross a plasma membrane least effectively?

Molecule AB with an octanol-water partition coefficient of 0.5

A channel that opens in response to the binding of a specific molecule, which is usually not the solute that passes through the channel called a___?

ligand-gated channel

An important aspect of transport by facilitated transporters and pumps is ?

conformation change

The sodium-potassium pump makes the cell interior more __ by pumping __ sodium ions out of the cell for every __ potassium ions pumped in,

negative, 3, 2

What is the distinguishing characteristic of a P-type pump?

it must be phosphorylated during the cycle

In the Na+/glucose cotransporter,__ moving down its gradient drives the transport of __ against its gradient.

glucose, Na⁺ ions

What factors directly or indirectly determine the transition temperature?

a, b, c

In what way can a given solute get through a membrane?

a, c, d

What advantage do the cristae confer on the mitochondria?

They greatly increase the surface area for aerobic respiration machinery

Mitochondria are sites of the __?

A,b,c,d

What happens to the carbons of pyruvate that do not enter the Krebs cycle?

They are converted to CO₂

Where are most of the enzymes of the Krebs Cycle located?

in the soluble phase of the mitochondrial matrix

What is the terminal electron acceptor of the electron-transport chain in cells undergoing aerobic respiration?

O₂

Essay Question: List the major steps for aerobic metabolism(cellular respiration), location of where the reactions take place and the major reactants and products for each step.

Essay Question: Describe the difference between prokaryotic cells and eukaryotic cells. Use a table to organize.

The fundamental difference between prokaryotic and eukaryotic cells is cellular organization. Prokaryotic cells lack internal compartmentalization, meaning essential processes like transcription and translation occur in the same space. In contrast, eukaryotic cells use membrane-bound organelles to compartmentalize functions, allowing for greater efficiency, regulation, and specialization.

This increased complexity in eukaryotic cells supports multicellularity, tissue specialization, and advanced physiological processes, while prokaryotic cells are highly efficient and adaptable despite their simplicity.

Feature	Prokaryotic Cells	Eukaryotic Cells

Cell type

Simple, primitive cells

Complex, advanced cells

Nucleus

No true nucleus; DNA is in a nucleoid region

True nucleus enclosed by a nuclear membrane

DNA structure

Single, circular DNA molecule; no histones (most)

Multiple, linear chromosomes with histone proteins

Membrane-bound organelles

Absent

Present (mitochondria, ER, Golgi, lysosomes, etc.)

Cell size

Smaller

Ribosomes

70S ribosomes (smaller)

80S ribosomes (larger)

Cell wall

Usually present; made of peptidoglycan (bacteria)

Present in plants (cellulose) and fungi (chitin); absent in animals

Cytoskeleton

Very simple or absent

Well-developed cytoskeleton

Mode of reproduction

Asexual (binary fission)

Asexual (mitosis) and sexual (meiosis)

Essay Question: Substances (solute, ions, nutrients, etc.) can be transported into or out of the cells across the plasma membrane via different mechanisms. List the name of the mechanisms and describe the major features of each.

1) Passive transport by simple diffusion

No energy required; high to low concentration; movement down the concentration gradient; w/without protein channels

2) Passive transport by facilitated diffusion

No energy required; requires channels or carrier proteins; moves down concentration gradient; highly selective of molecules

3) Passive transport by osmosis (moves water through membrane)

No energy required; water moves from high concentration to low concentration; uses aquaporin proteins

1) Primary Active Transport

2) Secondary Active Transport

3) Active Transport via pumps

Analytical Question: In the middle of the winter, the membranes from a tissue sample from an organism dwelling in a pond are analyzed for their phospholipid content. In the middle of the summer, another tissue sample is taken from the same type of organism and the membrane lipid content determined. The lipid content has changed. How has it changed and why?

The lipid content shifts towards more unsaturated phospholipids in the winter and more saturated phospholipids in the summer in order to maintain optimal membrane fluidity under changing temperature conditions.

Analytical Question: You are studying a transport molecule. It appears to bind temporarily to the molecule to be transported. During normal transport, no energy is expended. An increase in the concentration of the normally transported molecule in the presence of a constant concentration of the inhibitor increases the rate of transport, what kind of transport is described?

Facilitated diffusion using carrier proteins. The process does not require energy, it involves temporary binding of the transported molecules, it moves down the concentration gradient, and it has an inhibitor that is fighting for the same binding site.

Bonus Question: List the basic properties of cells. You can list up to 10.

1) Cells are alive and can die

2) Cells Are Highly Complex and Organized

3) Cells Possess a Genetic Program and the Means to

Use It

4) Cells Are Capable of Producing More of Themselves

5) Cells Acquire and Utilize Energy

6) Cells Carry Out a Variety of Chemical Reactions

7) Cells Engage in Mechanical Activities

8) Cells Are Able to Respond to Stimuli

9) Cells Are Capable of Self-Regulation

10) Cells Evolve

What are the 4 tenets of cell theory?

1) All organisms are composed of one or more cell

2) The cell is the structural unit of life

3) Cells arise from pre-existing cells by division

4) Cells contain genetic information in the form of DNA, and

that information is passed from parent to daughter cell.

What is Mitosis?

Symmetric Division

Asymmetric Division

Difference between Pro. & Euk: Complexity

Prokaryotes:

Eukaryotes:

Difference between Pro. & Euk: Cell Wall

Prokaryotes:

Eukaryotes:

Difference between Pro. & Euk: Plasma Membrane

Prokaryotes:

Eukaryotes:

Difference between Pro. & Euk: Cytoplasm

Prokaryotes:

Eukaryotes:

Difference between Pro. & Euk: Genetic Material

Prokaryotes: Circular DNA& Chromosomes; no chromatid

Eukaryotes: Linear DNA; Chromatid made of DNA

Prokaryotes: a nucleoid region

Eukaryotes: a membrane-bound nucleus

Difference between Pro. & Euk: Cellular Reproduction

Prokaryotes: Divide by Binary Fission

Eukaryotes: Divide by Mitosis

Difference between Pro. & Euk: Organism Reproduction

Prokaryotes: Asexual; conjugation

Eukaryotes: Sexual

Difference between Pro. & Euk: Locomotion

Prokaryotes: Multiple flagella; no cilia; simple structure

Eukaryotes: Less or a single flagella; multiple cilia; complex structure

What are the 2 types of Eukaryotes?

Unicellular and Multicellular

What are the characteristics of Multicellular eukaryotes?

What are the characteristics of Unicellular eukaryotes?

What is Cell Replacement Therapy?

The process of infusing stem cells in patients whose cells lose normal function.

What are stem cells?

Undifferentiated cells capable of self-renewal and differentiation into other types of cells; asymmetric division

What are the characteristics of Adult stem cells?

Multipotent; can be used to replace damaged or diseased adult tissue; Can differentiate into other types, but not every type

What are the characteristics of Embryonic stem cells?

Only exist in the embryo; more powerful; Pluripotent; Can differentiate into every type of cell in the body

What are the 7 functions of the plasma membrane?

1) Compartmentalization

2) Scaffold for biochemical activities

3) Providing a selectively permeable barrier

4) Transporting solutes

5) Responding to external stimuli

6) Intercellular interaction

7) Energy transduction

Amphipathic

Membrane lipids that has both a Hydrophilic region and a hydrophobic region

3 main types of membrane lipids

1) Phosphoglycerides

2) Sphingolipids

3) Cholesterol

Phosphoglycerides

diacylglycerides with small functional head groups linked to the glycerol backbone by phosphate ester bonds.

Sphingolipids

ceramides formed by the attachment of sphingosine to fatty acids.

Cholesterol

a smaller and less amphipathic lipid that is only found in animals

The 3 membrane protein classifications

1) Integral proteins (transmembrane proteins)

2) Peripheral proteins

3) Lipid-anchored proteins

Integral Proteins

Differentiation

The process by which a relatively unspecialized cell becomes highly specialized

Denaturation

Renaturation

Organelles found in both eukaryotes and prokaryotes

Organelles found only in Prokaryotes

Organelles found only in Eukaryotes

Lipid-anchored Proteins

Found outside the bilayer on either the extracellular or cytoplasmic surface; are covalently linked to a membrane lipid situated within the bilayer.

What are the ion channels?

What are Aquaporins?

Small membrane integral proteins that form specialized protein channels that allow passive movement of water; not permeable to H+

Explain the fluid mosaic model

Functions of Peripheral proteins

• Mechanical/ structural support for the membrane.

• Anchor for integral proteins.

• Enzymes

• Acts as specialized coats (to prevent damage to cells)

• Acts as a bridge to transmit transmembrane signals

• Protection

Liquid crystal phase

Above the transition temperature

Solid crystal(gel) phase

Below the transition temperature

Transition temperature

Nonelectrolytes

depends on the concentration gradient

Electrolytes

depends on the electrochemical gradient