Lecture Quiz #2

Question 1

What is a molecule?

Answer 1

Molecules are atoms joined together by chemical bonds.

Question 2

How does an ionic bond differ from a covalent bond?

Answer 2

A covalent bond is the bo
nd formed when atoms share electrons. An ionic bond is formed when
electrons are transferred from one atom to another.

Question 3

n what circumstance is a hydrogen bond commonly used?

Answer 3

Hydrogen bonds are formed mostly between molecules (for example, betwee
n water molecules)
and act to stabilize the solution. Hydrogen bonding is key to water’s unique properties as a universal
solvent and a medium for the life processes. Hydrogen bonds can also form between parts of the same
molecule. This works to stabilize
and hold the shape of large, complex molecules such as proteins and
DNA

Question 4

What are the three types of chemical reactions?

Answer 4

Synthesis reaction: A new, more complex chemical is made from multiple, simpler chemicals.
Decomposition reaction: A
complex substance breaks down into its simpler parts.
Exchange reaction: Certain atoms are exchanged between molecules. It is a combination of a synthesis
and a decomposition reaction.

Question 5

What factors influence the rate of chemical reactions? Be able to list three
.

Answer 5

The rate of a chemical reaction is influenced by: (1) the availability of the reactants, referred to
as the concentration of reactants. The more reactants that are available, the more likely they will come in contact and be able to react with one another. (2) Thereaction to happen. Some reactions have a higher activation energy and require an input of more energy for the reaction to occur. These reactions will occur at a slower pace. (4) Certain reactions require the presence of a
catalyst. In living organisms, catalysts are usually special proteins that hold the reactants together so they may interact. The catalyst protein is not destroyed or used up by the reaction, and the reaction speed is increased when there are more catalyst proteins present. These special catalyst
proteins are called enzymes temperature of the environment. When the temperature increases, the speed of molecular movement increases and the chance of molecules meeting improves. Temperature also increases the velocity at which the reactants meet and the velocity provides the energy for the reaction. (3) Activation energy
is the energy required for the reaction to happen. Some reactions have a higher activation energy and require an input of more energy for thereaction to occur. These reactions will occur at a slower pace. (4) Certain reactions require the presence of a catalyst. In living organisms, catalysts are usually special proteins that hold the reactants together so they may interact. The catalyst protein is not destroyed or used up by thereaction, and the reaction speed is increased when there are more catalyst proteins present. These special catalyst
proteins are called enzymes

Question 6

What is the difference between organic and inorganic compounds?
Are only organic compounds
necessary for life?

Answer 6

No
The primary difference between organic compounds and inorganic compounds is that organic compounds always contain carbon while most inorganic compounds do not contain carbon. Also, almost all organic compounds contain carbon-hydrogen or C-H bonds

Question 7

What are the three types of inorganic molecules that are important for life?

Answer 7

Water, salts, and acids and bases

Question 8

What are the four types of organic molecules that are important for life?

Answer 8

Carbohydrates, lipids, proteins, and nucleic acids

Question 9

Why is water called a “polar” molecule?

Answer 9

Because it’s atom has a larger charge

Question 10

How is an ion different from an atom?

Answer 10

Atoms are neutral. They contain the same number of protons as electrons. An ion is an electrically charged particle produced by either removing electrons from a neutral atom to yield a positive ion or adding electrons to a neutral atom to yield a negative ion

Question 11

What is an electrolyte? What are some examples of electrolytes?

Answer 11

a liquid or gel that contains ions and can be decomposed by electrolysis, e.g., that present in a battery. Sodium, potassium, and calcium are examples of electrolytes

Question 12

Which type of compound is known as a proton donor? Is it an acid or base?

Answer 12

Acid

Question 13

Is a solution with a pH of 8.5 acidic or basic?

Answer 13

Basic

Question 14

How does a weak acid act as a buffer?

Answer 14

It helps the cell maintain a neutral pH by not allowing excessive hydrogen or hydroxyl ions to
accumulate. In water, a weak acid will initially ionize into: (1) free hydrogen (H+) ions, (2) a weak
base product, and (3) remaining intact weak acid molecules. The pH of the solution is not changed
much because some of the chemical remains in acid form and some in the form of a weak base.

Question 15

What three elements are found in all carbohydrates?

Answer 15

C, H, O

Question 16

What is the name of a simple sugar?

Answer 16

monosaccharides

Question 17

What process joins multiple simple sugars?

Answer 17

Dehydration synthesis

Question 18

What is another name for a complex, multiunit carbohydrate?

Answer 18

Polysaccharide

Question 19

What three elements are found in all lipids?

Answer 19

C, O, H

Question 20

Which lipids are polar: a) neutral fats or b)

phospholipids?

Answer 20

Phospholipids

Question 21

What is the function of lipids in the body?

Answer 21

Store energy

Question 22

What are the building blocks for proteins?

Answer 22

Amino acids

Question 23

What is the name of the bond holding two amino acids together?

Answer 23

Amino acids are held together by peptide bonds, which are covalent bonds formed through dehydration synthesis or condensation reactions. It forms between the amino terminus of one amino acid’s backbone and the carboxyl terminus of another amino acid’s backbone.

Question 24

What is a peptide?

Answer 24

A peptide is a molecule consisting of two or more amino acids in which the carboxyl group of
one acid is linked to the amino group of the other

Question 25

How does an enzyme work?

Answer 25

Enzymes speed up or catalyze chemical reactions without being destroyed or altered. Enzymes
are specific to the reaction they catalyze and the substrates (the substances they act upon) they use

Question 26

How does a nucleotide differ from a nucleic acid?

Answer 26

A nucleotide is a single molecule containing a sugar, phosphate group and nitrogen base.

Nucleic acids are polymers of nucleotides [contain repeating units of nucleotides] linked by phosphodiester bonds.

Question 27

What three parts compose a nucleotide?

Answer 27

· a 5-carbon sugar (called deoxyribose)
· a phosphate group (1 phosphorus atom joined to 4 oxygen atoms)
· one of 4 nitrogenous bases (Adenine, Guanine, Cytosine, Thymine)

Question 28

How many nitrogenous bases are there?

Answer 28

There are five nitrogen bases: adenine (A), guanine (G), cytosine (C), uracil (U), and thymine
(T)

Question 29

Explain the structure of DNA

.

Answer 29

DNA molecules consist of two parallel strands of the nucleotides A, G, C, and T. The strands
are connected by hydrogen bonds between the nitrogenous bases. Each nitrogenous base can only hydrogen bond with one other specific nitrogenous base. Adenine can bond only with thymine, and guanine can bond only with cytosine. The two strands of bonded nucleic acid twist around each other in a spiral called a double helix. The order of the nucleotides is unique to each individual and is carriedin every cell of the individual.

Question 30

How does an ATP molecule differ from a nucleotide

Answer 30

ATP is an RNA nucleotide containing the nitrogen base adenine with two additional phosphategroups attached.

Question 31

How does an ATP molecule supply a cell with energy

to do work?

Answer 31

As a nutrient (for example, glucose) is catabolized, the energy created is stored in ATP molecules. ATP stores this energy in the bonds between its phosphate groups. When these bonds are broken, that energy is released from the ATP molecule. To use the energy stored in ATP, enzymes must move the terminal phosphate group to another molecule. The receiving molecule is then called phosphorylated and temporarily has energy to do some work. During this process the ATP molecule loses a phosphate group and becomes ADP. Another phosphate group can be used, resulting in thecreation of a molecule of AMP. As more glucose and other nutrients are metabolized,phosphategroups are joined to AMP creating a renewed source of ATP.

Question 32

What are the basic cellular functions that define life?

Answer 32

Cells can grow, develop, reproduce, adapt, become influenced by outside stimuli, maintain a
stable internal environment, and convert food into usable energy. Each cell carries vital genetic
material that governs its own development, metabolism, and specialization.

Question 33

What are the basic cellular functions that define life?

Answer 33

Cells can grow, develop, reproduce, adapt, become influenced by outside stimuli, maintain a
stable internal environment, and convert food into usable energy. Each cell carries vital genetic
material that governs its own development, metabolism, and specialization.

Question 34

What is the difference between a prokaryote and a eukaryote?

Answer 34

• prokaryotic cells do not have a nucleus and eukaryotic cells do.
• prokaryotic cells lack some organelles and eukaryotic cells do not.
• prokaryotic cells are not found in humans and eukaryotic cells are.
• prokaryotic cells are always unicellular and eukaryotic cells are often multicellular.
• prokaryotic cells reproduce/divide by binary fission and eukaryotic cells reproduce/divide by mitosis/meiosis

Question 35

Why are cells called “cells”?

Answer 35

n 1665 Robert Hooke examined the structure of cork. He noticed that the cork was composed
of thousands of small “rooms,” and he called these rooms cells. The word cell is from the Latin
cella meaning “little chamber.” Hooke did not know at the time that the actual cell as we know it had died and that he was examining the honeycomblike structure of the remaining cell walls. Other researchers began to study plant
and animal tissues and continued to use the word
cell to describe the basic parts of these tissues

Question 36

Why aren’t cells the size of watermelons?

Answer 36

Smaller cells have smaller nutritional requirements than large cells but have a proportionately
larger surface through which they can absorb the substances they need. Thus smaller cells are able to complete their metabolic functions more rapidly and efficiently than large cells. If cells were the size
of watermelons, they would not be able to take in nutrients fast enough to feed themselves and would
die. A second limiting factor in cell size is related to the governing capability of the nucleus. A single
nucleus can control the metabolic activity of a small cell better than it could a large one. Also, the
more active a cell is, the greater its metabolic needs. Therefore it is not surprising that very large cells or cells that are more active, such as cardiac and skeletal muscle cells, have two or more nuclei

Question 37

Name three structures that all mammalian cells possess.

Answer 37

Cytoplasm nucleus cell membrane

Question 38

Be able to describe key components of the lipid
bilayer of the cell membrane. Which part is
hydrophobic and which part is hydrophilic?

Answer 38

The side of the lipid bilayer facing the outside of the cell is hydrophilic and the side f
acing the inside of the cell is hydrophobic .

Question 39

What types of protein are found in the cell membrane?

Answer 39

The cell membrane contains structural and globular proteins. Globular proteins include integral and peripheral proteins.

Question 40

Where are the protein

s located and their role?

Answer 40

Proteins are found everywhere …. every nook and corner in the cell .. most things are made from proteins as well …. here’s what they do

Proteins can have several functions.
1. As enzymes they have a catalytic function.
2. As antibodies they can regulate the immune system.
3. Signaling pathways .. involved in signaling pathways that regulate all kinds of functions in the body.
Ex. Metabolism.
Also transcription and translattion is regulated. For example during transcription, proteins are called transcription factors and they regulate all aspects of transcription and gene expression.,
There are also proteins that regulate all steps of the cell cycle.
4. Proteins can be messengers. Thus these messengers will bring messages from other parts of body. for example insulin.
5. There are receptors that are proteins that will accept the message and relate it to other factors inside the protein so that a certain function can happen.
6. Scaffolding proteins … large proteins that have multiple functional and activation sites that will bind various proteins together and create a network of signaling cascade and also bring proteins that otherwise will not interact closer together so that they can interact.
7. Structural proteins … some proteins make up the structure … when considering the mass these are the largest amount of proteins in the body. Example elastin and collagen that make up the skin or actin and myosin in muscle cells.

These are some I can think from top of my head. Theres more.

Question 41

What is the glycocalyx?

Answer 41

Glycocalyx is a general term referring to extracellular polymeric material produced by some bacteria, epithelia and other cells. For instance, the slime on the outside of a fish is considered to be a glycocalyx. …

Question 42

What are membrane receptors and what do they do?

Answer 42

Membrane receptors are integral proteins and glycoproteins that act as binding sites on the cell
surface. Some of them play a vital role in
cell
-
to
-
cell recognition
.
This is particularly important during
cell
-
mediated immune responses and assists bacteria and viruses in finding preferred “target” cells.

Question 43

How are cilia and flagella different?

Answer 43

Cilia occur in large numbers on the expo
sed surface of some cells. They are shorter than flagella
and measure only about 10 μm long. They move synchronously, one after the other, creating waves of
motion that propel fluid, mucus, and debris across the cell surface. Cilia are best known for their
important functions (1) in the upper respiratory tract, where they propel bacteria and mucus away from
the lungs, and (2) in the oviduct, where their beating motion pulls the ovulated egg away from the
ovary and into the opening of the oviduct.
Flagella
generally occur singly and are significantly longer than cilia. They are typically attached to
individual cells and propel the cell forward by undulating. Flagella move cells through fluid, whereas
cilia move fluid across cell surfaces. The tail of a sper
m cell is an example of a flagellum

Question 44

Which are found more commonly in mammalian cells: cilia or flagella?

Answer 44

Cilia

Question 45

What are the four principal components of cytoplasm?

Answer 45

Cytosol, cytoskeleton, organelles, and inclusions

Question 46

What is cytosol and what kind of molecules are found in it?

Answer 46

Cytosol is the fluid of the cell It is a viscous, semitransparent liquid composed of dissolved
electrolytes, amino acids, and simple sugars. Proteins are also suspended in the cytosol and give it its thick, jellylike consistency.

Question 47

What is the cytoskeleton and what is its function?

Answer 47

The cytoskeleton is a structural feature of eukaryotic cells that was revealed by advanced microscopy. It consists of an extensive three-dimensional network of interconnected filaments and tubules that extends throughout the cytosol, from the nucleus to the inner surface of the cell membrane. These filaments and tubules determine cell shape and facilitate a variety of cell movements.

Question 48

How many types of fibers make up the cytoskeleton? Can you name them? How do they function differently?

Answer 48

Three different types of fibers compose the cytoskeleton, all of which are made of protein. The
fibers are microtubules, intermediate fibers, and microfilaments. Microtubules form secure “cables” to which mitochondria, lysosomes, and secretory granules attach. Proteins that act as “motors” move the attached organelles along the microtubule from one location in the cell to another. Because microtubules act as the “railroad tracks” for organelle travel, they can be easily disassembled and then reassembled to form new paths or take a new direction. Intermediate fibers are woven, ropelike fibers that possess high tensile strength and are able to resist pulling forces on the cell by acting as internal guy wires. These fibers are the toughest and most permanent element of the cytoskeleton. Microfilaments play a key rol
e in the cell’s ability to change shape, break apart during cell division, and form outpouchings and involutions. In most cells, microfilaments are assembled where and when needed.

Question 49

How does each of the organelles discussed and
listed in the Table in your chapter function within the
cell? (example Mitochondrion).
Be able to list and describe their functions and recognize their shapes. (see chapter and class notes)

Answer 49

The mitochondrion is known as the “powerhouse” of the cell because it produces 95% of the
energy that fuels the cell. In the mitochondria, large nutrient molecules, such as glucose, are processed and broken down into smaller ones that can be used intracellularly to fuel most metabolic processes. The mitochondrion is also where cell
respiration takes place: oxygen is consumed, and carbon dioxide is excreted. Numerous biochemical reactions (e.g., amino acid and fatty acid catabolism, respiratory electron transport, oxidative phosphorylation, and the oxidative reactions of the citric acid cycle) occur in the mitochondria.
The ribosome is an important site for protein synthesis. Soluble protein intended for intracellular use is manufactured on ribosomes that are evenly distributed throughout the cytoskeleton. Protein intended for use in the plasma membrane or meant for cellular export is synthesized on ribosomes attached to the endoplasmic reticulum.
Rough endoplasmic reticulum(ER) is involved in the production of protein, which is assembled by the ribosomes that stud the ER during prote
in synthesis (giving it its “rough” appearance). Newly manufactured molecules of protein are moved internally into passageways known as
cisternae, Latin for “reservoirs.” Here the proteins are modified before being moved on to the Golgi apparatus for further modification and packaging.
Smooth ER, which is connected to rough ER, is active in the synthesis and storage of lipids,
particularly phospholipids and steroids, and is therefore seen in large quantities in gland cells. In liver cells, smooth ER may also function to eliminate drugs and break down glycogen into glucose.
The Golgi apparatus acts as a modification, packaging, and distribution center for molecules destined for either secretion or intracellular use. It also functions in polysaccharide synt
hesis and in the coupling of polysaccharides to proteins (glycoproteins) on the cell surface.
The lysosome’s principal responsibilities are the breakdown of nutrient molecules into usable smaller units and the digestion of intracellular debris. Lysosomes may also release their enzymes outside the cell to assist with the breakdown of extracellular material. In addition, lysosomal digestion is responsible for decreasing the size of body tissues (for example, shrinkage of the uterus after parturition and atrophy of muscles in paralyzed animals).
Peroxisomes are commonly found in liver and kidney cells and are important in the detoxification of various molecules. Peroxisomes contain enzymes that use oxygen to detoxify a number of harmful substances, including alcohol and formaldehyde. They also assist in the removal of free radicals, which are normal products of cellular metabolism but can be harmful to the cell in large quantities because they interfere with the structures of proteins, lipids, and nucleic acids

Question 50

Why do inclusions vary in appearance? What function do they perform?

Answer 50

The appearance of inclusions varies depending on what they contain and whether or not they
have an envelope. They store substances the cell eventually uses

Question 51

Why is the nucleus considered the “CEO of operations”?

Answer 51

The nucleus is considered the CEO of the cell because its primary functions are to maintain the
hereditary information of the species and to control cellular activities through protein synthesis. The hereditary information (DNA) the nucleus contains enables the cell to divide and produce an identical
daughter cell. By controlling cellular activities, the nucleus controls the well being of the cell.

Question 52

Can a cell that does not contain a nucleus live as long as a cell that does contain one? Why or why
not?

Answer 52

No, because the cell cannot repair itself, divide, or make proteins or enzymes without a nucleus.

Question 53

Describe the nuclear envelope. How is it different from the cell membrane?

Answer 53

The plasma membrane, which is the membrane surrounding the cell, is a single phospholipid bilayer. Embedded in it are proteins and other compounds, such as cholesterol.

The nuclear envelope is double. This means that there are two phospholipid bilayers,with embedded proteins. In places the membranes connect, leaving a pore. This pore is important for permitting large molecules in and out of the nucleus, such as messenger RNA (mRNA) leaving the nucleus, and proteins synthesized in the cytoplasm entering for assembly into ribosomal subunits. Each pore is surrounded by proteins forming a nuclear pore complex.

The outer membrane of the nuclear envelope is continuous with the rough endoplasmic reticulum.

Nuclear membrane is Nuclear envelope which covers the nucleus. It separate the nucleus from the rest of the cell. It decides what goes In and out of the NUCLEUS. The nuclear membrane is attached somewhat to ER while cell membrane is not obviously. It also has pores that cell membrane does not.

Cell membrane surrounds the cell itself and decides what goes in and out of the CELL.

Question 54

How do histones play a role in gene regulation?

Answer 54

A single strand of DNA winds around eight histone molecules forming a granule called a nucleosome The nucleosomes are held together by short strands of DNA called linker DNA. Not only
do the histone proteins help keep the DNA strand organized and untangled, they also expose small
sections of the DNA (genes) to the outside nucleoplasm. By changing shape, the histones can exposedifferent genes at different times.

Question 55

What is the significance of the nucleolus? What happens in that region of the nucleus?

Answer 55

It is composed of nucleic acids and proteins and is responsible for the transcription and assembly of ribosomal ribonucleic acid (rRNA). rRNA is a major component of the cellular organelles known as ribosomes, which manufacture proteins for use by the rest of the cell.

Question 56

Where is most of the water in animals found?

Answer 56

Most of the water in animals is found inside the cell and is called intracellular fluid

Question 57

What is diffusion? Is it an active or a passive membrane process?

Answer 57

Diffusion can be defined as the process of moving down the concentration gradient from an area
of high concentration to a region of low concentration. Diffusion is a passive membrane process.

Question 58

What molecules are more likely to diffuse into a cell? What three principles are involved
indetermining ability to diffuse into a cell?

Answer 58

Water, oxygen, and carbon dioxide are more likely to diffuse into a cell. The three principles
involved are:
1. Molecular size: Ver
y small molecules like water (H 2O) may pass through cellular membrane pores
(approximately 0.8 nm in diameter), but larger molecules like glucose cannot.
2. Lipid solubility: Lipid soluble molecules (e.g., alcohol and steroids) and dissolved gases (e.g.,
oxygen [O2] and carbon dioxide [CO 2
]) can pass through the lipid bilayer with ease, whereas other molecules may not.
3. Molecular charge: Ions are small in size, but their charge prevents easy passage through the
membrane pores. Specialized pores called
channels selectively allow certain ions to pass through but not others.

Question 59

How is facilitated diffusion different from simple diffusion?

Answer 59

Simple diffusion moves molecules from an area of higher concentration to an area of lower concentration without an input of energy. Facilitated diffusion follows the same rules as regular diffusion (higher to lower concentration and no energy input), but uses protein carrier molecules to allow substances that are fat soluble to diffuse through the cell membrane.

Question 60

What effect does a hypotonic solution have on a cell? What passive membrane process causes this
effect?

Answer 60

If the extracellular fluid is hypotonic, the inside of the cell is more concentrated than the outside.
In this scenario, water flows into the cell and causes it to swell and possibly burst. This effect is due tothe process known as osmosis

Question 61

When is a membrane process considered “active”?

Answer 61

The movement of molecules and subs
tances across the cell membrane is considered active when
the cell is required to use energy (ATP). They cannot move through the plasma membrane passively.

Question 62

How do electrolytes enter the cell?

Answer 62

Electrolytes enter cells via active transport withou

t the assistance of a concentration gradient

Question 63

Describe how sodium and potassium enter and exit the cell.

Answer 63

Because of the concentration gradient of sodium (Na) and potassium (K), potassium tends to
diffuse out of the cell and sodiu
m diffuses in. To maintain appropriate levels of intracellular potassium and extracellular sodium, the cell must pump potassium into the cell and move out sodium. Because diffusion is ongoing, the active transport system must work continuously. The rate of transport depends on the concentration of sodium ions in the cell. ATP is provided by cellular respiration and, with the assistance of the enzyme ATPase, is broken down for use as energy on the inner surface of the cell membrane. The pump can cycle several times using just one molecule of ATP, so that forevery molecule of ATP, two K
ions are moved intracellularly and three Na
ions are moved extracellularly

Question 64

Describe the three types of endocytosis.

Answer 64

The three types of endocytosis are phagocyto
sis, pinocytosis, and receptor mediated
endocytosis.

Question 65

What is the difference between excretion and secretion? These are both examples of what?

Answer 65

Excretion is the movement of waste products from the intracellular to the extracellular
environment, and secretion is the movement of manufactured molecules from the intracellular to the extracellular environment. Both are examples of exocytosis

Question 66

What are the principal ions involved in maintaining a cell’s resting membrane potential?

Answer 66

Sodium and

potassium

Question 67

Is there normally a higher concentration of sodium inside or outside of the cell? Where is there a
higher concentration of potassium?

Answer 67

Sodium is 10 to 20 times higher outside the cell than it is inside. Potassium is 10 to 20 times
higher inside the cell than outside.

Question 68

What is the term for mRNA formation?

Answer 68

Messenger RNA (mRNA) formation is known as transcription

Question 69

What are codons and what role do they play in transcription?

Answer 69

A codon is a set of three adjacent nucleot
ides in an mRNA molecule that specifies the
incorporation of an amino acid into a polypeptide chain or that signals the end of polypeptidesynthesis

Question 70

Can you describe the events that occur in translation?

Answer 70

A ribosome binds to the beginning of th
e mRNA strand. Transfer RNA (tRNA) molecules move near the ribosome. The tRNA anticodon is paired with the appropriate codon on the mRNA molecule.
An amino acid carried by the tRNA molecule is released and linked to the neighboring amino acid.
The ribosome continues to move along the mRNA molecule until all of the codons have been paired.
As the developing chain of amino acids lengthens, it coils and folds into the structure of a functional
protein. When translation is complete, the new protein is released and later modified. The ribosome, tRNA, and mRNA are free to repeat the process and form more of the same type of protein.