Unit 1 Learning Objectives

Question 1

Define the terms: anatomy and physiology and explain how anatomy and physiology
complement each other.

Answer 1

1) Anatomy: Examining the structure of the human body
2) Physiology: The study of function of the human body
3) Anatomy and physiology complement each other because of the unity of form and function

Question 2

Describe gross anatomy and give 3 examples

Answer 2

Gross anatomy is a type of anatomy that studies structures that can be seen with the eyes. 3 examples of gross anatomy being applied in medicine are dissection, exploratory surgery, and medical imaging.

Question 3

Name 3 areas of microscopic anatomy and describe them

Answer 3

3 areas of anatomy that study microscopic structures too small to see with your eye are histology, cytology, and ultrastructure.
Histology is the examination of tissues under a microscope.
Cytology is the study of structure and function of cells.
Ultrastructure is the study of viewing detail under an electron microscope.

Question 4

Name 3 areas of physiology and describe them

Answer 4

3 subdisciplines of physiology are Neurophysiology (physiology of the nervous system) Endocrinology (physiology of hormones) and Pathophysiology (the study of the mechanisms of disease).

Question 5

Describe the subdiscipline of comparative physiology and why it’s so important

Answer 5

Comparative physiology is another subdiscipline of physiology and is the study of another species to learn about body functions. Comparative physiology is important to physiology as a whole because physiology, unlike anatomy, requires live subjects due to the fact that you cannot observe function on a cadaver, so often relies on animals to perform research that will then become preliminary research for human medicine.

Question 6

Describe some aspects of experimental design that help ensure objective and reliable
results.

Answer 6

Having a control group and an experimental group, replicating the experiment multiple times, and ensuring there’s no cross-contamination.

Question 7

Give the levels of human structure from the most complex to the simplest (hierarchy of
complexity).

Answer 7

Organism, organ system, organ, tissue, cell, organelle, molecule, atom.
*Note: Organelles, molecules, and atoms are not considered to be alive; cells are the smallest unit of life

Question 8

List the nine characteristics of life.

Answer 8

Organization, cellular composition, metabolism, responsiveness, movement, homeostasis, reproduction, development, and evolution of a population.

Question 9

Define homeostasis

Answer 9

Maintaining relatively stable internal conditions [regardless of external conditions].

Question 10

Define a gradient and give examples of gradients in the human body.

Answer 10

A gradient is defined as a difference in chemical concentration, charge, temperature, or pressure between two points.
Examples:
1) blood flowing from a place of higher pressure (near the heart) to a place of lower pressure, sodium-potassium gradients
2) heat flowing from an area of high heat (inside the body) to an area of low heat (outside the body)
3) dietary glucose flowing from an area of high concentration to low concentration (into intestinal cells).

Question 11

Describe which direction do gradients flow naturally and what would be necessary if you
went “against” or “up” a gradient.

Answer 11

Molecules naturally flow down gradients (from areas of high concentration to low concentration). If you went against the gradient (from an area of low concentration to high), that would require a cell to use energy (ATP).

Question 12

Define the terms: element, atom, molecule, and compound.

Answer 12

Element: The simplest form of matter with unique properties.
Atom: building blocks for each element.
Molecule: chemical particle composed of two or more atoms united by a chemical bond.
Compound: molecule composed of two or more different elements.

Question 13

List the six elements that comprise 98.5% of our body weight.

Answer 13

Oxygen (O), Carbon (C ), Hydrogen (H), Nitrogen (N), Calcium (Ca), and Phosphorus (P).

Question 14

Describe the three particles that make up an atom and their arrangement in an atom.

Answer 14

Neutrons have no charge, and they determine atomic mass (number of protons + number of neutrons = atomic mass). Atoms of an element with a different number of neutrons than protons are called isotopes.
Protons have a positive charge, and they determine the identity of an element as well as its atomic number (atomic number = number of protons the atom has).
Electrons have a negative charge. Atoms of an element with a different number of electrons than protons are called ions (or electrolyte), and they have a positive (cation) or negative charge (anion) (more electrons = more negative).
Neutrons and protons are found in the nucleus of an atom, whereas electrons are found in shells (or energy levels) around the nucleus. The first energy level is full with 2 electrons, and the second and third levels are full with 8 electrons. Electrons in the outermost level are called valence electrons.

Question 15

Define the terms isotope and radioactive isotope.

Answer 15

Isotope: when an atom has a different number of neutrons than protons.
Radioactive isotope: an isotope that disintegrates over time and gives off energy.

Question 16

Describe ways we can use radioactive isotopes in medicine

Answer 16

They can be used for radiation therapy and diagnostic procedures. This includes PET scans, using I-131 determine size and activity of the thyroid gland, Hida scans (Tc-99 technetium with a ½ life of 6 hours), Cobalt-60 for cancer.
Other examples of radioactive isotopes include UV radiation, X-rays, alpha particles, beta particles, gamma rays.

Question 17

Discuss how cations and anions are formed.

Answer 17

If an atom gains an electron, then it becomes an anion (negatively charged). If an atom loses an electron, then it becomes a cation (positively charged). This only happens to atoms without a full outer shell (i.e. atoms that are not noble gas elements).

Question 18

List each type of chemical bond in order of relative strength from strongest to weakest.

Answer 18

Covalent bonds, ionic bonds, hydrogen bonds.

Question 19

Discuss the “octet rule” and how we apply it to predict which type of chemical bond will
be formed.

Answer 19

The octet rule is the concept that atoms gain or lose electrons to have full outer shell. We use this rule to help figure out if two atoms are going to share electrons and form a covalent bond, or if one atom will donate an electron to the other atom and form an ionic bond. For example we can determine if two atoms are eligible to become a cation and an anion (i.e. if one atom only has one electron in an outer shell) and by using the octet rule, we know that the atom wants to get rid of that electron, so if it gets near an atom with one missing electron, it will donate that electron to the atom with the missing electron, and the one the electron was donated to becomes an anion and the one that did the donating becomes a cation (and now both atoms have full outer shells), and now those two atoms have formed an ionic bond.

Question 20

Explain the mechanism of ionic bonds, non-polar covalent bonds, polar covalent bonds,
and hydrogen bonds.

Answer 20

Ionic bonds: The donation of an electron from one atom to another; a bond between a cation and an anion.
Non-polar covalent bonds: Two or more atoms share electrons equally.
Polar covalent bonds: Two or more atoms share electrons unequally.
Hydrogen bonds: A weak charge attraction between a slightly positive hydrogen and a slightly negative oxygen (or nitrogen).

Question 21

List a biological example of each type of bond

Answer 21

Hydrogen bonding: The bases in DNA form hydrogen bonds (ex: there’s two hydrogen bonds between A and T and three hydrogen bonds between C and G).
Ionic bonding: Ionic bonds help shape tertiary and quaternary structures of proteins, and NaCl is found in the human body and has an ionic bond.
Covalent bonding: Water molecules found in the human body are formed with covalent bonds, peptide bonds formed between amino acids, covalent bonds within each linear strand of DNA.

Question 22

Define the terms mixture, solution, solute, solvent, colloid, and suspension.

Answer 22

Mixture: physically blended but not chemically combined (ex: body fluids are mixtures of chemicals).
Solution: A homogenous mixture of two or more substances (a solute and solvent) in relative amounts that can be varied continuously up to the limit of solubility.
Solute: the substance that dissolves in a solvent to produce a homogeneous mixture.
Solvent: the substance in which a solute dissolves to produce a homogeneous mixture.
Colloid: a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance.
Suspension: a heterogeneous mixture of a fluid that contains solid particles sufficiently large for sedimentation.

Question 23

Describe the five biologically important properties of water.

Answer 23

– Solvency: ability to dissolve other chemicals; water is referred to as the ‘universal solvent’.
– Cohesion: water molecules cling to each other; water is very cohesive due to its hydrogen bonds. This in turn causes surface tension.
– Adhesion: water adheres to other substances (ex: water adheres to large membranes reducing friction around organs).
– Chemical reactivity: ability to participate in chemical reactions; water ionizes into and ionizes many other chemicals (acids and salts).
– Thermal stability:Water has high heat capacity (absorbs and releases large amounts of heat before changing temperature); this is because hydrogen bonds inhibit temperature increases by
inhibiting molecular motion. This property is what helps keep the internal temperature of our bodies stable.

Question 24

Describe which types of molecules will easily mix with water and which will not.

Answer 24

Molecules with polar covalent bonds will easily mix with water, but molecules with nonpolar covalent bonds will not.

Question 25

Define the terms pH, acid, base, and buffer.

Answer 25

pH: A measure of hydrogen ion concentration.
Acid: A chemical species that donates protons or hydrogen ions and/or accepts electrons. Has a low pH.
Base: A chemical species that donates electrons, accepts protons, or releases hydroxide (OH-) ions in aqueous solution. Has a high pH.
Buffer: A solution that can resist pH change upon the addition of an acid or a base by neutralizing small amounts of that acid or base.

Question 26

Define energy and work.

Answer 26

Energy: The capacity to do work [move something].
Work: To move something.

Question 27

Differentiate between potential energy and kinetic energy.

Answer 27

Potential energy is energy stored in an object, but not currently doing work, whereas kinetic energy is the energy of motion and doing work.

Question 28

Differentiate between decomposition reactions and synthesis reactions and be able to
give examples of each

Answer 28

Decomposition reactions are where a large molecule breaks down into two or more smaller ones (ex: AB > A + B), whereas synthesis reactions are where two or more small molecules combine to form a larger one (A + B > AB).

Question 29

List the three factors that will increase reaction rates.

Answer 29

Reaction rates increase when the reactants are more concentrated, the temperature rises, and when a catalyst is present.

Question 30

Define metabolism and its two subdivisions.

Answer 30

Metabolism: all chemical reactions of the body.
Catabolism: energy-releasing decomposition reactions that break covalent bonds and produce smaller molecules.
Anabolism: energy-storing synthesis reactions that require energy input (ex the production of protein or fat)
Side note: Anabolism is driven by energy released by catabolism.

Question 31

Define the term organic molecule.

Answer 31

compounds containing carbon.

Question 32

Explain the relationship between macromolecules, monomers, and polymers.

Answer 32

Macromolecules are made up of polymers, and polymers are made up of monomers.

Question 33

Describe hydrolysis and dehydration synthesis.

Answer 33

Hydrolysis is splitting a polymer by the addition of water. Dehydration synthesis is when monomers covalently bind together to form a polymer with the removal of a water molecule

Question 34

Identify the monomers and polymers of carbohydrates and their functions.

Answer 34

Monomers: Monosaccharides: Glucose, galactose, and fructose are examples, and they are simple sugars that are produced by the digestion of complex carbohydrates. Glucose functions as blood sugar in the body.
Disaccharides: Sucrose (table sugar) = Glucose + fructose, Lactose (sugar in milk) = Glucose + galactose, Maltose (grain products) = Glucose + glucose.
Polysaccharides: Ex: Glycogen is a glucose polymer that is stored in the liver and skeletal muscles.

Question 35

Describe how all lipids are related.

Answer 35

In all lipids, either part of or the entire molecule is hydrophobic.

Question 36

Describe the structure and functions of triglycerides (neutral fats) and phospholipids.

Answer 36

Triglycerides are three fatty acids linked to glycerol, and their primary function is energy storage (contain 2x more energy than carbs or proteins), and they also help with insulation and padding (shock absorption (adipose tissue)).
Phospholipids are similar to neutral fats except one fatty acid is replaced by a phosphate group; consists of two hydrophobic fatty acid tails and a hydrophilic phosphate head. They make up the phospholipid bilayer of the cell membrane.

Question 37

Describe how triglycerides are transported in the human body.

Answer 37

Because triglycerides are hydrophobic, they are packaged within intestinal cells along with cholesterol molecules in phospholipid vesicles called chylomicrons, which allows them to move within the aqueous environment of the lymphatic and circulatory systems.

Question 38

Describe what “parent” steroid from which the other steroids are synthesized.

Answer 38

Cholesterol, which is important for nervous system function and structural integrity of all cell membranes; 15% of our cholesterol comes from our diet.

Question 39

Describe the structure of an amino acid

Answer 39

Amino acids have a central carbon with three attachments (Amino group (NH2), carboxyl group (—COOH), and radical group (R group)). Amino acids only differ in the R group.

Question 40

Describe the formation of peptide bonds

Answer 40

Peptide bonds are bonds between two amino acids that joins their carboxyl groups together, and they’re formed by dehydration synthesis; the resulting chain is called a peptide.

Question 41

Explain the four levels of organization of protein structure and how these contribute to
so many different proteins.

Answer 41

Primary: Sequence of amino acids joined by peptide bonds.
Secondary: Alpha helix or beta sheet formed by hydrogen bonding
Tertiary: Folding and coiling due to interactions among R groups and between R groups and surrounding water. This is what makes proteins really unique.
Quaternary: Association of two or more polypeptide chains with each other.
These structures create what is called a conformation, which is the unique, three-dimensional shape of protein, which is crucial to function. So many proteins exist because there are many different ways proteins can fold in each level of organization of protein structure.

Question 42

Differentiate between a fibrous protein and a globular protein.

Answer 42

Fibrous proteins are generally composed of long and narrow strands and have a structural role (they are something). Examples include keratin and collagen.
Globular proteins generally have a more compact and rounded shape and have functional roles (they do something). Examples include carriers, catalysis, motor proteins, etc.

Question 43

Discuss the two major ways to denature a protein, and define denaturation.

Answer 43

Extreme heat or pH can denature proteins. Denaturation is an extreme conformational change that destroys a protein’s ability to function.

Question 44

Describe some functions of proteins in the human body

Answer 44

Structure (ex: keratin and collagen)
Communication (ex: some hormones and receptors)
Membrane transport (ex: channel proteins in cell membranes govern what passes)
Carriers (ex: carrier proteins transport solutes to the other side of membranes)
Catalysis (ex: most enzymes are globular proteins)
Recognition and protection (ex: antibodies are proteins)
Movement (ex: motor proteins, which are molecules with the ability to change shape repeatedly)
Cell adhesion (ex: proteins bind cells together and keeps tissues from falling apart. ex: sperm to egg).

Question 45

Define an enzyme and describe the characteristics of enzymes.

Answer 45

Enzyme: proteins that function as biological catalysts and allow reactions to occur rapidly at body temperature; they do this by lowering the activation energy. They’re named for the substrate it acts upon plus the suffix -ase. They’re reusable because enzymes are not consumed by the reactions and they work at an astonishing speed (one enzyme molecule can consume millions of substrate molecules per minute). However, temperature, pH and other factors can change enzyme shape and function, which can alter the ability of the enzyme to bind to the substrate

Question 46

Describe the three nucleic acids in the human body and their basic function.

Answer 46

DNA: contain millions of nucleotides and constitutes genes.
RNA: follows DNA instructions to assemble proteins
ATP: the body’s energy currency.

Question 47

Describe the composition of nucleotides.

Answer 47

They contain a nitrogenous base (Adenine, Guanine, Cytosine, Thymine or Uracil), a sugar (ribose or deoxyribose), and one or more phosphate groups.

Question 48

The components of cell theory are:

Answer 48

–All organisms composed of cells and cell products; organisms that don’t contain cells do not exist.
–The cell is the simplest structural and functional unit of life; anything simpler than a cell is not considered to be alive.
–An organism’s structure and functions are due to the activities of cells.
–Cells come only from preexisting cells, they don’t just spontaneously appear
–Cells of all species exhibit biochemical similarities

Question 49

List the three components of a cell that can be viewed with a light microscope.

Answer 49

You can see the nucleus, where the plasma membrane is, and the cytoplasm.

Question 50

Define extracellular fluid, intracellular fluid, interstitial fluid.

Answer 50

Extracellular fluid: Fluid within the body outside of the cells.
Intracellular fluid: Fluid contained within cells.
Interstitial fluid: Fluid between cells and tissues; one of the two major extracellular fluids in the body (the other one is plasma).

Question 51

Differentiate between cytoplasm and cytosol.

Answer 51

Cytoplasm contains the organelles; cytosol does not. Cytosol is the word used to describe only the aqueous components of the cytoplasm.

Question 52

Describe the structure of the plasma membrane.

Answer 52

The plasma membrane is the border of the cell, and it is arranged in a bilayer of phospholipids, with the hydrophobic tails of the phospholipids facing the interior of the plasma membrane. It also can contain integral proteins, and integral transmembrane proteins like protein channels, as well as cholesterol, peripheral proteins, and carbohydrate chains (carbohydrate chains are attached to the exterior side). There is a fuzzy exterior to the plasma membrane called the glycocalyx as well, and it provides the cell with protection, immunity to infection, and defense against cancer.

Question 53

Explain the functions of the lipid, protein, and carbohydrate components of the plasma membrane.

Answer 53

The lipid component makes up the phospholipid bilayer of the plasma membrane, which constitutes 75% of the plasma membrane.
Proteins are 2% of the molecules within the plasma membrane, but make up 50% of the membrane’s weight. Proteins can act in the plasma membrane as receptors, enzymes, channels, carriers, cell-identity markers, and cell-adhesion molecules.
The carbohydrate chains help with cell recognition and adhesion, and they allow for cell-cell signaling and help in cell-pathogen interactions.

Question 54

List what types of molecules pass through the phospholipid bilayer and which types
must use a protein channel or carrier.

Answer 54

Types of molecules that can pass through: Non-polar molecules, hydrophobic molecules, small molecules,
Types that need to use a protein channel or carrier: Polar molecules, hydrophilic molecules, large molecules, and ions/ charged molecules.

Question 55

Discuss how the fluid mosaic model describes the plasma membrane.

Answer 55

The plasma membrane is incredibly flexible and if poked, the phospholipids will move vertically, but they will always reorient themselves into a bilayer because of the hydrophilic head and hydrophobic tails.

Question 56

Differentiate between integral proteins and peripheral proteins.

Answer 56

Integral proteins: penetrate the plasma membrane.

Peripheral proteins: lie on the surface of the plasma membrane.

Question 57

Describe the types and functions of gated channels

Answer 57

Ligand-gated channels are needed to respond to chemical messengers (like neurotransmitters) by opening or closing, voltage-gated channels are needed to respond to electrical signals (like electrical nerve impulses) by opening or closing, and mechanically-gated channels are needed to respond to physical stress on the cell by opening or closing (they are also an example of a stretch receptor). Channel proteins within the plasma membrane in general govern what goes into and out of a cell (excluding things that can pass straight through the plasma membrane).

Question 58

What do carrier proteins do?

Answer 58

Carrier proteins transport solutes to other side of membrane

Question 59

Describe the structure and functions of microvilli

Answer 59

Microvilli are extensions of the membrane (1–2 μm) that give the membrane 15 to 40 times more surface area, which helps in absorption. Thus, they’re best developed in cells specialized in absorption. They can be very dense and appear as a fringe; known as “brush border”.

Question 60

Describe the structure and functions of cilia

Answer 60

Cilia are hair-like processes that are 7–10 μm long. Motile cilia are found in the respiratory tract, uterine tubes, ventricles of brain, and ducts of testes; they beat in waves sweeping material across a surface in one direction.

Question 61

Describe the structure and functions of flagella

Answer 61

Flagella have a whip-like structure and are much longer than cilium. The tail of a sperm is the only functional flagellum in humans. Their movement is undulating, snake-like, corkscrew, with no power stroke and recovery strokes.

Question 62

Describe the structure and functions of pseudopods

Answer 62

Pseudopods are continually changing extensions of the cell that vary in shape and size, and can be used for cellular locomotion and capturing foreign particles.

Question 63

Define simple diffusion and give an example

Answer 63

Simple diffusion is defined as the net movement of particles from place of high concentration to place of lower concentration; it happens because of constant, spontaneous molecular motion; molecules collide and bounce off each other. It does not require energy or a membrane, and only non-polar hydrophobic molecules can enter cells using this method. Ex: oxygen permeating the cell membranes of lung cells.

Question 64

Define osmosis and give an example

Answer 64

Osmosis is similar to simple diffusion, but it requires a selectively permeable membrane to be present. It’s defined as the diffusion of water through a selectively permeable membrane from an area of high concentration to an area of low concentration. It does not require energy, and does not use a carrier protein like facilitated diffusion. Ex: water moving into my interstitial cells after I drink water.

Question 65

Define facilitated diffusion and give an example

Answer 65

Facilitated diffusion, like simple diffusion, is the net movement of something from areas of high concentration to low concentration. However, it moves a solute from a place of high concentration to a place of lower concentration using a carrier protein. It does not require energy. This is usually used to allow hydrophilic polar molecules to enter cells. Ex: the movement of glucose from the bloodstream and into cells, the diffusion of water into cells through aquaporins.

Question 66

Define filtration and give examples

Answer 66

Filtration is where particles are driven through a membrane by physical pressure. Examples of this would be the filtration of water and small solutes through gaps in capillary walls, the delivery of water and nutrients to tissues, and the removal of waste from capillaries in the kidneys. It does not require energy from the cell either, like simple diffusion, osmosis, and facilitated diffusion.

Question 67

Define primary active transport and give examples

Answer 67

Primary active transport is when a carrier protein moves the solute through a membrane up (against) its concentration gradient. Because it is moving against the concentration gradient (unlike simple diffusion, osmosis, facilitated diffusion, and filtration), this process requires energy. Examples would be the calcium pump (uniport) and the sodium–potassium pump (antiport).

Question 68

Define vesicular transport and give examples

Answer 68

Vesicular transport is the movement of large particles, fluid droplets, or numerous molecules at once through the membrane in vesicles (bubble-like enclosures of membrane). Like primary active transport, it requires energy. Examples of this include phagocytosis (cells eating things), exocytosis (cells removing things), and pinocytosis (cells drinking things).

Question 69

Describe the factors that influence the rate of diffusion.

Answer 69

1) Temperature: ^ temp = ^ motion of particles = ^ rate
2) Molecular weight: larger molecules move slower
3) Steepness of concentrated gradient: ^ difference = ^ rate
4) Membrane surface area: ^ area = ^ rate
5) Membrane permeability: ^ permeability = ^ rate

Question 70

Define osmolarity and tonicity.

Answer 70

Osmolarity: The measure of total concentration of solute particles.
Tonicity: The concentration of non-permeating solutes.

Question 71

Discuss the two conditions necessary for osmosis

Answer 71

Osmosis requires the presence of a concentration gradient, as well as the presence of a selectively permeable membrane.

Question 72

Determine which type of solution (hypertonic, isotonic, or hypotonic) will cause crenation or cytolysis/hemolysis.

Answer 72

Hypertonic solutions cause crenation (cells shriveling from water leaving the cell), hypotonic solutions cause cytolysis/hemolysis (cells exploding from water entering the cell), and isotonic solutions do not do anything to cells since there is no concentration gradient.

Question 73

Compare and contrast osmosis using simple diffusion versus facilitated diffusion (aquaporins).

Answer 73

Osmosis is very slow, like a dripping faucet, when using only simple diffusion. However, osmosis through facilitated diffusion allows water to pour into or out of a cell quickly. The more aquaporins a cell has, the faster water moves in and out of the cell.

Question 74

Explain the difference between uniports, symports, and antiports and give examples of each.

Answer 74

Uniports moves molecules across the membrane independent of other molecules,
Antiports move two types of molecules across the membrane in opposite directions, and
Symports move two different molecules in the same direction.
Examples: calcium pump (uniport), the sodium–potassium pump (antiport), and moving glucose up its concentration gradient by using the energy from the movement of sodium ions that are moving down their gradient (symport).

Question 75

Distinguish between phagocytosis, pinocytosis, and receptor-mediated endocytosis.

Answer 75

Phagocytosis: Cells eating things/ engulfing large particles; a type of endocytosis.
Pinocytosis: Cells drinking things; a type of endocytosis.
Receptor-mediated endocytosis: A more selective type of endocytosis that enables cells to take in specific molecules that bind to extracellular receptors.

Question 76

Discuss the three types of protein fibers used for the cytoskeleton and the functions of each type.

Answer 76

Intermediate filaments are thicker and stiffer than microfilaments and participate in cell-to-cell adhesion; they give the cell its shape.
Microfilaments are about 6 nm thick and are made of the protein actin. They are widespread throughout the cell but especially concentrated in a fibrous mat called the terminal web (membrane skeleton) on the exterior side of the plasma membrane, and they provide support to the cell.
Microtubules (25 nm in diameter) are cylinders made of 13 parallel strands called protofilaments. Each protofilament is a long chain of globular proteins called tubulin. Microtubules radiate from an area of the cell called the centrosome. They hold organelles in place, form bundles that maintain cell shape and rigidity, and act somewhat like monorail tracks.

Question 77

Discuss the structure and functions of peroxisomes

Answer 77

Detoxify certain harmful chemicals, enclose reactions that make toxic byproducts. Abundant in the cells found in the liver and kidneys.

Question 78

Discuss the structure and functions of lysosomes

Answer 78

A package of enzymes bound by a membrane, they aid in intracellular hydrolytic digestion, phagocytosis, and autolysis.

Question 79

Discuss the structure and functions of centrioles

Answer 79

They form the mitotic spindle during cell division, unpaired centrioles form basic structure of cilia and flagella.

Question 80

Discuss the structure and functions of mitochondria

Answer 80

A kidney-bean shaped organelle specialized for synthesizing ATP.

Question 81

Discuss the structure and functions of the golgi complex

Answer 81

It receives newly synthesized proteins from
rough ER, then sorts proteins, modifies proteins, and packages them into vesicles. Some vesicles become lysosomes, some vesicles migrate to plasma membrane and fuse to it, and some become secretory vesicles that store a protein product for later release.

Question 82

Discuss the structure and functions of ribosomes

Answer 82

They’re small granules of protein and RNA that “read” coded genetic messages (messenger RNA) and assemble amino acids into proteins specified by the code.

Question 83

Discuss the structure and functions of the smooth ER

Answer 83

A system of channels enclosed by a membrane, it synthesizes steroids and other lipids, detoxifies alcohol and other drugs, and stores calcium.

Question 84

Discuss the structure and functions of the rough ER

Answer 84

It is composed of parallel, flattened sacs covered with ribosomes, and it synthesizes proteins and packages proteins for transport.

Question 85

Discuss the structure and functions of the nucleus

Answer 85

Also known as the “brain of the cell”, it’s the largest organelle and it controls all cellular activity. It is enclosed in a the nuclear membrane, which is double membrane with pores surrounding the nucleus. Contains chromatin and chromosomes.

Question 86

Discuss the structure and functions of the cytosol

Answer 86

The aqueous component of the cytoplasm of a cell; also called intracellular fluid/ ICF.

Question 87

Discuss the structure and functions of the plasma membrane

Answer 87

Made up of phospholipids, proteins, and carbohydrate tails. Defines cell boundaries, governs interactions with other cells, and controls passage of materials in and out of the cell.

Question 88

Discuss the structure and functions of the cytoplasm

Answer 88

Contains the organelles, cytoskeleton, inclusions (stored or foreign particles), and cytosol (intracellular fluid, ICF)

Question 89

Define autolysis, autophagy, and phagocytosis

Answer 89

Phagocytosis: Cells eating things/ engulfing large particles; a type of endocytosis.
Autolysis: The destruction of cells or tissues by their own enzymes.
Autophagy: The digestion and disposal of surplus or nonvital organelles and other cell components in order to recycle their nutrients to more important cell needs.

Question 90

Describe how lysosomes relate to the processes of autolysis, autophagy, and phagocytosis

Answer 90

Lysosomes help aid in phagocytosis (the cell eating things); after a neutrosome captures a bacteria in a phagosome, a lysosome merges with the phagosome, converting it to a phagolysosome, and contributes enzymes that destroy the invader. They also help aid in autolysis by releasing enzymes that will kill the cell. Lysosomes also digest and dispose of surplus or nonvital organelles and other cell components in order to recycle their nutrients to more important cell needs, which is autophagy.

Question 91

Compare and contrast nuclear DNA and mitochondrial DNA.

Answer 91

Mitochondrial DNA (mtDNA) is a small, circular molecule that is more visually similar to the circular DNA of bacteria, not the linear DNA found in the cell nucleus. mtDNA also replicates independently from nuclear DNA. Mitochondrial DNA consists of 16,569 base pairs, comprising 37 genes, which is quite small when compared to the over 3 billion base pairs and about 20,000 genes in nuclear DNA. Both DNA and mtDNA are heritable, but you only inherit mtDNA from your mother, whereas you inherit your nuclear DNA from both of your parents.

Question 92

Describe the structure of DNA.

Answer 92

DNA has a double helix structure and it’s made up of nitrogenous bases united by
hydrogen bonds. A purine on one strand is always bound to a pyrimidine on the other;
also, A–T have two hydrogen bonds, whereas C–G have three hydrogen bonds.
The law of complementary base pairing states that one strand determines the base
sequence of the other.

Question 93

Explain how DNA and histone proteins are organized to form the chromosomes.

Answer 93

The DNA first winds around spools of proteins called histones to form the little granules (core particles), then the chromatin then folds into successive zigzags, loops, and coils, getting thicker and shorter as it does so. Then the DNA, which is 2 nm in diameter, is consolidated into chromatin strands 150 times thicker and 1,000 times shorter than the naked DNA. Finally, each chromosome is packed into its own spheroidal region of the nucleus, called a chromosome territory

Question 94

Discuss the three specific parts of a DNA nucleotide.

Answer 94

Each DNA nucleotide contains a sugar (deoxyribose), a phosphate group, and one nitrogenous base (A, T, C, or G).

Question 95

List the purine nitrogenous bases and the pyrimidine nitrogenous bases and describe
which purine base will make hydrogen bonds with which pyrimidine base.

Answer 95

Purines: Adenine & Guanine
Pyrimidines: Thymine & Cytosine
The purine adenine forms two hydrogen bonds with the pyrimidine thymine, and the purine guanine forms three hydrogen bonds with the pyrimidine cytosine.

Question 96

Define the terms chromatin, chromosomes, and sister chromatids.

Answer 96

Chromatin: fine filamentous DNA material complexed with proteins.
Chromosomes: A complex of DNA and protein carrying the genetic material of a cell’s nucleus; consists of two sister chromatids. Normally there are 46 chromosomes in the nucleus of each cell except germ cells.
Sister chromatids: Two parallel filaments of identical DNA

Question 97

Discuss the fours differences between DNA and RNA.

Answer 97

RNA differs from DNA in that it’s single stranded (it consists of just one nucleotide chain and not a double helix like DNA), ribose replaces deoxyribose as the sugar, uracil replaces thymine as a nitrogenous base, and it functions mainly in cytoplasm.

Question 98

State the current definition of a gene

Answer 98

An information-containing segment of DNA that codes for synthesizing one or more proteins.

Question 99

Describe how DNA codes for protein structure.

Answer 99

DNA triplets relate to the mRNA codons and those, in turn, relate to the amino acids of a protein; in other words, the nucleotide sequence in the DNA determines the amino acid sequence of a protein.

Question 100

Describe the assembly of amino acids into a protein.

Answer 100

1) DNA double helix exists.
2) There are seven base triplets on the template strand of DNA
3) The corresponding codons of mRNA are transcribed from the DNA triplets
4) The anticodons of tRNA then bind to the mRNA codons
5) The amino acids are carried by those six tRNA molecules
6) The amino acids are linked into a peptide chain through peptide bonds; this is the primary structure of a protein.
7) Secondary structure formation: Alpha helix or beta sheet formed by hydrogen bonding
8) Tertiary structure formation: Folding and coiling due to interactions among R groups and between R groups and surrounding water. This is what makes proteins really unique.
9) Quaternary structure formation: Association of two or more polypeptide chains with each other.

Question 101

Discuss the roles of messenger RNA, ribosomal RNA, and transfer RNA.

Answer 101

mRNA: carries code from nucleus to cytoplasm during translation.
tRNA: after the mRNA brings the code to the cytoplasm during translation, tRNA then delivers a single amino acid to the ribosome for it to be added to growing protein chain
rRNA: ribosomes are largely made up of rRNA and enzymes; after tRNA delivers the amino acid to the ribosome, the ribosome adds the amino acid to the protein chain.
The essential function of the three principal RNAs is to interpret the code in DNA and use those instructions to synthesize proteins

Question 102

Describe where triplets, codons, and anticodons are found and be able to correctly give
the codon and anticodon if given a triplet code.

Answer 102

Seven base triplets are found in the template strand of DNA, and corresponding codons are found in the mRNA. Anticodons are found in tRNA.

Question 103

Explain the process of transcription

Answer 103

In the nucleus, RNA polymerase reads bases from one strand of DNA, and then makes corresponding mRNA.

Question 104

Describe the process of translation

Answer 104

1) Initiation
Initiator tRNA (bearing methionine) pairs with start codon. Ribosome pulls mRNA molecule through it like a ribbon. When start codon (AUG) is reached, protein synthesis begins
2) Elongation 
Next, tRNA (with its amino acid) binds to the ribosome while its anticodon pairs with the next codon of mRNA. A peptide bond forms between methionine and the second amino acid.
The ribosome slides to read the next codon.
Next, tRNA with the appropriate anticodon brings its amino acid to the ribosome.
Another peptide bond forms (between the 2nd and 3rd amino acids). Process continually repeats, extending the peptide into a protein
3) Termination
Ribosome reaches stop codon, finished protein breaks away from ribosome, ribosome dissociates into two subunit

Question 105

Explain what happens to a protein after its amino acid sequence has been synthesized.

Answer 105

1) Protein is formed by ribosomes on rough ER.
2) Protein is packaged into transport vesicle, which buds from ER.
3) Transport vesicles fuse into clusters that unload the protein into the Golgi complex.
4) The golgi complex modifies the protein structure.
5) The golgi vesicle containing the finished protein is formed.
6) Lastly, secretory vesicles release the protein by exocytosis.

Question 106

Describe the process of DNA replication.

Answer 106

DNA unwinds from histones
An enzyme unzips a segment of the double helix exposing its nitrogenous bases
DNA polymerase builds new DNA strands
Newly made DNA wraps around histones

Question 107

Discuss the three phases of interphase and what occurs in each phase.

Answer 107

1) G1: first gap phase
The interval between cell birth (from division) and DNA replication. The cell carries out normal tasks and accumulates materials for next phase
2) S: synthesis phase
The cell replicates all nuclear DNA and duplicates centrioles
3) G2: second gap phase
The second gap phase; the interval between DNA replication and cell division. The cell repairs DNA replication errors, grows and synthesizes enzymes that control cell division

Question 108

Distinguish between the process of mitosis and cytokinesis.

Answer 108

Mitosis does not include the cell membrane splitting into two.

Question 109

Describe the prophase phase of mitosis

Answer 109

Genetic material condenses into compact chromosomes
46 chromosomes are made of two sister chromatids
Nuclear envelope disintegrates
Centrioles sprout spindle fibers (long microtubules)
Spindle fibers push centriole pairs apart
Some spindle fibers attach to kinetochores of centromeres of chromosomes

Question 110

Describe the four phases of mitosis and explain what occurs in each of the phases.

Answer 110

1) Prophase
Genetic material condenses into compact chromosomes
46 chromosomes are made of two sister chromatids
Nuclear envelope disintegrates
Centrioles sprout spindle fibers (long microtubules)
Spindle fibers push centriole pairs apart
Some spindle fibers attach to kinetochores of centromeres of chromosomes
2) Metaphase
Chromosomes are aligned on cell equator
Shorter microtubules from centrioles complete an aster which anchors itself to inside of cell membrane
3) Anaphase
Enzyme cleaves two sister chromatids apart at centromere
Single-stranded daughter chromosomes migrate to each pole of the cell as motor proteins in kinetochores crawl along spindle fibers
4) Telophase
Chromosomes cluster on each side of the cell
Rough ER makes new nuclear envelope around each cluster
Chromosomes uncoil to chromatin
Mitotic spindle disintegrates
Each nucleus forms nucleoli

Question 111

Describe the metaphase phase of mitosis

Answer 111

Chromosomes are aligned on cell equator

Shorter microtubules from centrioles complete an aster which anchors itself to inside of cell membrane

Question 112

Describe the anaphase phase of mitosis

Answer 112

Enzyme cleaves two sister chromatids apart at centromere
Single-stranded daughter chromosomes migrate to each pole of the cell as motor proteins in kinetochores crawl along spindle fibers

Question 113

Describe the telophase phase of mitosis

Answer 113

Chromosomes cluster on each side of the cell
Rough ER makes new nuclear envelope around each cluster
Chromosomes uncoil to chromatin
Mitotic spindle disintegrates
Each nucleus forms nucleoli

Question 114

List the 4 stages of mitosis in order

Answer 114

Prophase, metaphase, anaphase, telophase (PMAT)

Question 115

Discuss factors that would inhibit cell division

Answer 115

• They snugly contact neighboring cells
• Nutrients or growth factors are withdrawn
• They undergo contact inhibition—the cessation of cell division in response to contact with other cells

Question 116

Discuss factors that would promote cell division

Answer 116

• They have enough cytoplasm for two daughter cells
• They have replicated their DNA
• They have adequate supply of nutrients
• They are stimulated by growth factors (chemical signals)
• Neighboring cells die, opening up space