Intro to Molecular and Cellular Biology Exam #2

Identify the 4 macromolecules

Proteins, carbohydrates, lipids, nucleic acids

Identify the monomer for proteins

amino acids

Identify the monomer for carbohydrates

monosaccharides

Identify the monomer for lipids

hydrocarbons

Identify the monomer for nucleic acids

neucleotides

Identify the reaction by which macromolecule polymers are assembled from monomers

dehydration synthesis and condensation reactions

Draw the basic structure of an amino acid including the amino group, carboxyl group. central carbon, and amino acid side chain.

What are the 3 different groups of amino acid side chains

non polar, polar, electrically charged (acid/base)

Where is the N-terminus on an amino acid

The amino group

Where is the C-terminus on an amino acid

The carboxyl group

Where is the peptide bond between?

The end carbon and beginning nitrogen

What are the 4 levels of protein structure?

Primary, secondary, tertiary, quaternary

What bond contributes to primary structure?

Covalent peptide bonds

What bonds contribute to secondary structure?

Alpha helices and beta pleated sheets; hydrogen bonds

What bonds contribute to tertiary structure?

R-groups bonding together through covalent, hydrogen, ionic, and hydrophobic bonds/interactions.

What bonds contribute to quaternary structure?

Covalent, hydrogen, ionic, and hydrophobic bonds/reactions (not always present)

What is the structure and function of monosaccharides?

3-7 carbons in their backbone; form monomers/building blocks for longer and more complex carbohydrates

What are some examples of monosaccharides?

Glucose, ribose, fructose, galactose

Describe the structure and function of oligosaccharides

with 2-20 monosaccharides bonded together by glycosidic bonds

What are some examples of oligosaccharides?

Lactose, sucrose, maltose, trehalose

Describe the structures and function of polysaccharides

more than 20 monosaccharides bonded together by glycosidic bonds.

What are some examples of polysaccharides?

Cellulose, starch, chitin, hyaluron

Describe the structure and function of disaccharides

2 monosaccharide units join together with glycosidic bonds via condensation reaction, releasing a water molecule.

Identify the general molecular formula, functional groups, and bonds present in carbohydrates. What is the formula?

Cn(H2O)n

What are the two disaccharides?

Sucrose and lactose

What is the combination of monosaccharides of sucrose?

1 glucose molecule bonded to one fructose molecule. Used to transport energy from leaves to other tissues in plants.

What is the combination of monosaccharides of lactose?

1 glucose molecule bonded to 1 galactose molecule. It is a major carbohydrate found exclusively in the milk of mammals.

Distinguish between oligosaccharides and polysaccharides

Oligosaccharides are short chains of 3-10, function to recognize cells, cell signaling, cell-to-cell adhesion, and immune responses as well as being soluble.

Polysaccharides are longer chains of 10+ monosaccharides that are used for energy storage and structural support for organisms as well as being generally insoluble.

Identify the main types of poly saccharides

Starch, glycogen, cellulose, and chitin

Identify the glycosidic linkages and the function of starch

(Amylose) Alpha 1,4 linkages and is used for plant energy storage.

(Amylopectin) Alpha 1,4 and alpha 1,6 linkages which is used for plant energy storage.

Identify the glycosidic linkages and the function of glycogen

Alpha 1,4 and alpha 1,6 linkages that are used for energy storage in animals.

Identify the glycosidic linkages and the function of cellulose

Beta 1,4 linkages which are used for plant cell wall structural support.

Identify the glycosidic linkages and the function of chitin

Beta 1,4 linkages that are used for fungal cell walls and arthropod exoskeletons.

What are the three structures of biological lipids?

Triglycerides, steroids, and phospholipids

What is the structure of triglycerides?

Glycerol and three fatty acid tails connected by ester bonds.

What is the structure of steroids?

4 interconnected ring structure with different functional groups

What is the structure of phospholipids?

A phosphate head, 2 fatty acids tails held together by ester bonds.

What are the properties of saturated fatty acids?

Strictly single bonds, are fully saturated, are straight and flexible, pack tightly and closely together, have a higher melting point, solid at room temp, are primarily from animal fats, dairy, and tropical oils.

What are the properties of unsaturated fatty acids?

One or more double bond, have fewer hydrogen bonds, are kinked or bent at cis double bonds, packed loosely due to disruption, have a lower melting point, liquid at room temp, and are generally from plant oils, nuts, seeds, and marine fats.

How does membrane structure result in selective permeability?

The fluid mosaic model. Relies on amphipathic phospholipid bilayer and embedded transport proteins. Small non polar molecules will easily pass through, small uncharged polar molecules will mostly go through, large uncharged polar molecules will mostly not go through, and ions do not go through at all.

Explain the process of diffusion

Moves solutes (small/nonpolar) from high to low solute concentration. They do not require membrane protein or energy (ATP).

Explain the process of osmosis

Moves solvent (water molecules) from low to high solute concentration and does not need membrane proteins or energy. (They could be enhanced by ATP though.)

Explain the process of facilitated diffusion

Moves solutes (large/polar/charged) from high to low concentration and need membrane proteins (channels or carriers) but do not need energy (ATP).

Explain the process of active transport

The movement of molecules or ions across a cell membrane against their concentration gradient. (Move from low to high.) It requires ATP and membrane proteins to move.

How will a cell behave in a hypertonic solution?

The cell will shrivel and shrink since the water in on the outside.

How will a cell behave in a hypotonic solution?

The cell will swell and burst since the water is on the inside.

How will a cell behave in an isotonic solution?

The equal amount of water on the inside vs outside will keep the cell normal and healthy.

Identify the components and function of the phospholipid bilayer

Made up of lipids and is amphipathic. It establishes the basic boundary and selective permeability barrier.

Identify the components and function of proteins

Made of amino acid polymers and handle transport, signaling, enzymes, and structural anchoring.

Identify the components and function of cholesterol

Made of steroid lipids and buffers. Stabilizes membrane fluidity at varying temperatures.

Identify the components and function of glycoproteins

Made of proteins and carbohydrates. Serves as cellular ID tags for immune recognition and tissue binding.

Identify the components and function of glycolipids

Made of lipids and carbohydrates. Contributes to cell signaling, receptors, and outer membrane stability.

Describe the fluid mosaic model of the cell membrane

A dynamic, flexible double layer where proteins and other molecules float freely within a fluid lipid environment.

Identify factors that alter the fluidity of the membrane

High temps make the membrane loose.

Low temps make the membrane more brittle.

Unsaturated fatty acids have kinks or bends to keep the membrane fluid.

Saturated fatty acids have more rigid and tight structures to make the membrane less fluid.

What are the 4 types of membrane proteins?

Integral transmembrane proteins

Integral monotopic proteins

Peripheral proteins

Lipid-anchored proteins

What are the 6 functions of membrane proteins?

Transport

Enzymatic activity

Signal transduction

Cell to ell recognition

Intercellular joining

Attachment to cytoskeleton and extracellular matrix

What are the 4 types of cell junctions?

Adherens junctions

Desmosomes

Gap junctions

Hemidesmosomes

What is the composition and function of adherens junctions?

Catherine are their transmembrane proteins. Their anchor is microfilaments and their primary function is to resist shearing and form structural belts.

What is the composition and function of desmosomes?

Cadherins are their transmembrane protein. Their anchors are intermediate filaments (keratin) and their primary function is to spot welds and resist extreme pulling and stretching.

What is the composition and function of gap junctions?

Connexins are their transmembrane proteins. They don’t have anchors because they are a hollow channel and their primary function is to direct electrical or chemical communication.

What is the composition and function of hemidesmosomes?

Integrins are their transmembrane proteins. Their anchors are intermediate filaments (keratin) and their primary function is to anchor cells down to the extracellular matrix.

Identify the two most abundant proteins of the extracellular matrix

Collagen and elastin

What are the 3 categories of cytoskeleton proteins?

Microfilaments

Intermediate filaments

Microtubules

What is the shape and subunit of microfilaments?

A solid, twisted double-helix and the basic subunit is g-actin monomers.

What is the shape and subunit of intermediate filaments?

A thick, rope-like structural cable and their basic subunit is fibrous proteins (ex keratins, lamins)

What is the shape and subunit of microtubules?

Rigid, hollow cylinder shape and alpha/beta tublin dimers as their subunit.

Describe the basic tenets of cell theory

All living organisms are composed of 1+ cells

The cell is the basic structural and functional unit of life

All cells arise from pre-existing cells

What are the advantages of multicellularity?

Cellular specialization and division of labor

Larger physical size

Longer lifespan

Protection from the environment

Forming complex internal environments

Characteristics of prokaryotic cells

No nucleus

Single, circular chromosome for DNA structure

No membrane-bound organelles

Smaller ribosome size

Characteristics of eukaryotic cells

Nucleus

Multiple, linear chromosomes for DNA structure

Membrane-bound organelles

Larger ribosome size

Characteristics of animal cells

Plasma membrane only

Irregular, fluid, or round shape

No chloroplasts

Multiple, small, and temporary vacuoles

Centrioles and lysosomes

Energy storage in glycogen

Characteristics of plant cells

Plasma membrane and a rigid cellulose cell wall

Fixed, rigid, and rectangular shape

One large central vacuole

No centrioles and lysosomes

Energy storage in starch

Explain how the parts of the cell work together to enhance cellular function

Nucleus transcribes DNA. ribosomes read the mRNA. Rough ER folds the proteins and packages them. The cytoskeleton tracks serve as roads for motor proteins to pull vesicles. Golgi apparatus modifies, tags, and sorts the proteins. Plasma membrane fuses with the vesicles to release the finished proteins outside. The cytoplasm performs the initial breakdown of food. The mitochondria imports these fragments to generate ATP via cellular respiration. Transport proteins in the membrane use the ATP to pump vital nutrients into the cell against the gradients. The cytoskeleton provides an internal framework pushing against the plasma membrane. Cell junctions bind directly to fibers, linking the adjacent cells. The cytoskeleton guides the deposition of cellulose to form the outer cell wall in plants. Nucleus houses the chromosomes, which replicate their DNA. 

Which of the following is a characteristic of cholesterol?

It alters the fluidity of the membrane

Which of the following organelles contain an acidic environment?

Lysosomes

What is the function of the rough ER?

Protein synthesis

How many carbons do glucose, galactose, and fructose have?

6

How many carbons does ribose have?

5

How many carbons does glyceraldehyde have?

3

What contains thylakoid sacs?

Chloroplasts

What is surrounded by an envelope with pores?

Nucleus

What synthesizes proteins?

Rough ER

What is the shipping and receiving center of the cell?

Golgi Apparatus

What generates most of the energy in the cell?

Mitochondria

Keratin is an example of…

Intermediate filaments

What stores genetic information?

Nucleus

What contains many enzymes for degradation?

Lysosomes

What has cadherins and intermediate filaments?

Desmosomes

What contains an inner and outer membrane?

Mitochondria

What is a cytoskeletal protein that forms a hollow tube?

Microtubules

What synthesizes glycogen and steroids?

Smooth ER

What is made up of integral and matrix proteins?

Hemidesmosomes

What is made up of cadherin and actin?

Adherens junctions

What is composed of cellulose?

Cell wall

What steroid contributes to the fluidity of the cell membrane

Choloesterol

What is made up of connexins?

Gap juctions

What cytoskeletal protein is involved in muscle contraction?

Actin filament

Describe the nuclear envelope in animal cells

Double membrane with 2 phospholipid bilayers. Encloses and protects the cell. Separates the nucleus and cytoplasm. Provides structural support.

Describe nuclear pores in animal cells

Large protein channels that span across the nuclear envelope. Regulates traffic between the nucleoplasm and cytoplasm. Facilitates active transport.

Describe chromosomes in animal cells

Linear DNA strands tightly around packaging proteins. Stores the master genetic blueprint. Ensures accurate replication.