BIO1110 UNIT 1 EXAM 1 -- University of Memphis

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What are the laws of nature for thermodynamics?

1. Energy cannot be created or destroyed, only transferred.

2. Nature tends toward entropy.

Explain and diagram the central dogma.

DNA → (transcription) → RNA (translation) → Proteins

What are the essential features of all cells?

1. Cell Membrane

2. DNA

3. Metabolism/Ability to Process Energy

What did Francesco Redi and Louis Pasteur demonstrate and how?

Francesco Redi: Demonstrated that life does not occur spontaneously by leaving rotting meat in a sealed jar to see if flies would “appear.”

Louis Pasteur: Demonstrated that life does not occur spontaneously by having broth in a swan neck vs. straight neck flask; microbes only appeared in the open, straight neck flask.

Describe the types of chemical bonds & Van der Waals attraction.

1. Ionic: opposite charges

2. Covalent: sharing of electrons

3. Hydrogen: sharing of H atom

4. Van der Waals: electron cloud overlap

Describe how ionic and covalent bonds hold atoms together.

Ionic bonds feel attraction due to positive and negative ionic charge, while covalent bonds share electrons.

Explain the difference between polar covalent and nonpolar covalent bonds.

Polar covalent: unequal sharing of electrons

Nonpolar covalent: equal sharing of electrons

Explain how the structure of water leads to hydrogen bond formation.

The molecule that makes up water H2O, is covalently bonded; when attracted to another H2O molecule, H forms a hydrogen bond with the O of the other molecule due to its electronegativity.

Identify the properties of water and the biological benefits they provide.

1. Hydrophobic Repulsion: Allows for the phospholipid bilayer to form.

2. High Heat of Evaporation: Cooling effect

3. High Capacity for Heat: Stabilizes environments

4. Solubility: Allows molecules to be freely floating in a cell

5. Low Density of Ice: Allows aquatic animals to survive through winter; only the top layer of lakes freeze.

6. Cohesion/Adhesion: Allows leaves to collect water, capillary action

Give an example of how hydrogen bonding gives water the properties that make it essential for life.

1. Hydrophobic Repulsion: H2O is polar and rejects nonpolar molecules.

2. High Evap. & Capacity: Hydrogen bonds are difficult to break without increase of heat; makes water resistant to heat.

3. Solubility: H2O is polar and enjoys polar molecules and salts

4. Low Density of Ice: Highly organic structure of hexagonal hydrogen bonds while water is frozen.

5. Cohesion/Adhesion: H bonds are difficult to break

List the properties of life.

ROAR SHRMG

1. Reproduction

2. Organization

3. Adaptation

4. Sensitivity

5. Homeostasis

6. Regulation

7. Metabolism

8. Growth & Development

Describe natural selection.

Natural selection: occurs when there is a variation in the population that can be inherited.

Identify each level in the hierarchy of life.

1. Atom

2. Molecule

3. Cell

4. Tissue

5. Organ

6. Organ System

7. Organism

8. Population

9. Community

10. Ecosystem

11. Biome

12. Biosphere

Recognize the three domains of life.

Archaea, Bacteria, Eukarya

Explain the difference between a hypothesis and a theory.

Hypothesis: unsupported hypothetical claim or prediction based on an observation that can be tested

Theory: broad idea supported by a lot of evidence.

Explain what it means to “test a hypothesis” including the definition of control, placebo, independent variable, dependent variable, and constant.

To test a hypothesis is to develop an experiment based on the hypothesis via data collection or hands-on experimentation.

Control: Untouched component for comparison

Placebo: Inactive substance to test psychological response.

Independent Variable: controlled component

Dependent Variable: affected by independent

Constant: Variables that stay the same throughout

Explain how the structure and bonding of carbon contributes to biological macromolecules.

1. Carbon can form four covalent bonds with other atoms due to its four valence electrons, allowing for a variety of shapes (chains, rings) and complex molecules to form.

2. Allows for formation of biomolecules.

3. Carbon's ability to form long chains and complex branching structures allows for the creation of large macromolecules necessary for biological functions.

4. Carbon atoms can also form stable double and triple bonds, leading to further structural diversity within biological macromolecules.

5. The ability to form isomers (molecules with the same formula but different structures) contributes to the complexity and functionality of biological molecules.

Identify the four major organic molecules and their functions.

1. Carbohydrates (CHO, monosaccharides): Store energy & provide structural support

2. Lipids (CHO, fatty acids): Provide protections via cell membrane, store energy, and mandate communication

3. Proteins (CHON, amino acids): Complete work, provide structural support, and act as catalysts

4. DNA (CHONP, nucleotides): Store genetic information

Define isomers.

Isomers: Molecules with the same molecular formula but different structures.

Explain the difference between primary, secondary, tertiary, and quaternary protein structure.

Primary: pertains to the amino acid sequence, determines protein folding

Secondary: LOCAL interactions between amino acids; alpha helix and beta sheets

Tertiary: the three-dimensional shape of the protein as well as its function, long-range

Quaternary: only pertains to the subunits of a protein (2+), determines structure and function (ex., insulin, hemoglobin)

Describe what is meant by hydrophobic and hydrophilic R groups on amino acids and why they are important.

Refers to the polarity of the R compound attached to the amino acid and determines where the protein will be located and its function.

Describe the importance of enzymes in chemical reactions and how enzyme inhibitors affect their activity.

1. Enzymes speed up chemical reactions to facilitate reactions by lowering the activation energy

   1. Enzyme inhibitors bind to the enzyme and decrease its function; they can compete with the substrate, or change the enzyme’s shape by binding to another site; this slows down reactions.

Describe the role of protein tertiary structure in forming enzyme’s active site.

Tertiary structures determine the enzyme’s three-dimensional shape, therefore determining the shape and polarity of the active site.

Differentiate between DNA and RNA structures.

DNA: double-strand helix, ATGC

RNA: single strand, AUGC

Describe the structure of DNA and the type of bonds in base pairs.

1. DNA has a phosphate backbone attached to a 5-carbon deoxyribose sugar; attached to the sugar is the nitrogen base.

2. Linked by phosphodiester bonds.

3. Bases have two forms, PYRAMIDINES (Thymine, Cytosine, Uracil) and PURING (Adenine, Guanine)

What are the pyrimidine?

1. Single ring

2. Thymine, Cytosine, Uracil

What are the puring bases?

1. Double ring

2. Adenine and Guanine

Describe a simple sugar.

CHO chain.

Explain the difference between simple sugars (monosaccharides) and complex carbohydrates.

Simple Sugars: simplest CHO; single chain

Complex Carbohydrates: branched chains of monosaccharides with glycosidic bonds.

Describe the difference between saturated and unsaturated fatty acids and the structure of triglycerides.

Saturated: contains only CH single bonds; less mobile

Unsaturated: contains at least one double bond; more mobile; less hydrogens

Triglycerides: three glycerols connected by Van der Waals forces; long for large number of CH in a small volume; used for energy storage

Explain cell theory.

1. Cells are the fundamental unit of life.

2. All cells come from preexisting cells.

3. All organisms are made of cells.

Describe major differences between prokaryotic and eukaryotic cells.

PROKARYOTIC: free-floating DNA and ribosomes, smaller volume but greater SA:Volume ratio

BOTH: Membrane, cytoplasm, ribosomes, DNA

EUKARYOTIC: membrane-bound organelles, large with multiple compartments

Explain the importance of phospholipids and proteins in cell structure.

Phospholipids: amphipathic, form the cell membrane and regulate materials in and out of the cell, as well as support the cell; they can form micelle, bilayers, and liposomes.

Proteins: provide support for the cell with:

a. integral membrane proteins, which act as anchors, transporter, receptors, and enzymes

b. peripheral proteins, which promote communication and chaperone other proteins.

Explain the Fluid Mosaic Model of the cell membrane and how temperature, cholesterol, and fatty acid saturation affect membrane fluidity.

Fluid Mosaic Model: the plasma membrane has many different components, making it a fluid mosaic (i.e., proteins, cholesterol, sugars).

Temperature: high temperature increases fluidity, low temperature decreases fluidity

Cholesterol: At high temperatures, cholesterol decreases fluidity, and at low temperatures, cholesterol increases fluidity.

Saturated fatty acids: decrease fluidity

Unsaturated fatty acids: increase fluidity

Define amphipathic

Both hydrophilic and hydrophobic

Define the effect of amphipathic property of molecules on lipid and water solubility.

Amphipathic lipids are both water soluble and lipid soluble, meaning they can be arranged into a variety of membranes, such as liposomes, micelles, and bilayers based on water content and shape. This determines the functions and characteristics of membranes.

Predict the new direction of movement of molecules via diffusion along a concentration gradient.

High to low

Explain the difference between simple diffusion, facilitated diffusion, passive transport, primary active transport, and secondary active transport.

Simple Diffusion: movement from high to low concentrations with no ATP or proteins

Facilitated Diffusions: movement from high to low concentrations without ATP with the assistance of integral proteins

Passive Transport: movement through the cell membrane without use of ATP

Primary Active Transport: use of ATP to move ions against the concentration gradient

Secondary Active Transport: uses electrochemical gradients to move molecules against the concentration gradient; depends on active transport.

Identify the major differences between plant and animal cells.

PLANT CELLS: cell wall (structure), chloroplasts (photosynthesis),vacuoles (water absorption + rigidity), and plasmodesmata (connection). Larger, autotroph.

ANIMAL CELLS: lysosomes (waste disposal), centrioles, centrosomes (organize spindles for mitosis). Smaller, heterotroph.

Describe the kinds of membrane-enclosed organelles in eukaryotic cells.

Nucleus: contains genetic information

Mitochondria: generate energy

Endoplasmic Reticulum: responsible for protein and steroid production

Cell Membrane: protective barrier

Golgi apparatus: modifies and sorts proteins and lipids

Peroxisome/Lysosome: breaks down molecules and synthesize organic molecules

Describe the role of the cell wall in maintaining the size and shape of plant, fungal, and bacterial cells.

The cell wall provides support, is rigid, and resists expansion when water enters the cell due to TURGOR PRESSURE.

Explain the function of the nuclear envelope.

Inner and outer membrane with pores that allow molecules to enter and exit the cell (NLS & NES, short peptides).

Explain the function of the endoplasmic reticulum.

1. RER controls protein production and is covered with ribosomes.

2. SER controls fatty acid and phospholipid production.

Convoluted membrane allows for large amount of surface area.

Explain the function of the Golgi apparatus

1. Modifies and sorts proteins and lipids.

2. Post-translational modification: site for CHO addition to proteins and lipids (glycoproteins and glycolipids).

ER → cis Golgi → trans Golgi

Explain the function of lysosomes

1. Degrade macromolecules for intracellular digestion and recycling

2. Involved in apoptosis

3. Contain enzymes to break down all materials

Specialized vesicles from the Golgi.

Main characteristics of mitochondria and chloroplasts.

1. Specialized for harnessing energy

2. Grow and multiply independently because they have their own circular genome.

Explain the function of mitochondria.

1. Site of cellular respiration to convert compounds into ATP

2. maintains an electrochemical gradient and uses it to synthesize ATP

Explain the function of chloroplasts.

1. Site of photosynthesis, using CO2 to make CHO.

   1. Double membrane and thylakoid membrane with chlorophyll.

Describe how diffusion is affected by distance, surface area, and temperature.

1. Greater distances make diffusion more difficult.

2. Higher surface area: volume ratio benefits diffusion

3. Higher temperatures correlate with higher rates of diffusion.

Explain how cells overcome diffusion distance by changing their shape.

By changing their shape, cells increase their surface area in proportion to their volume, making them smaller, but more compact and able to diffuse materials effciently.

Identify the three types of filaments that compose the cytoskeleton and their functions.

Microfilaments: smallest, actin arranged in a helix; contract, crawl, cytokinesis, vesicle transport, and muscle contraction.

Intermediate Filaments (A-cell): intermediate, maintain cell shape and support; function depends on type

Microtubules: largest, made of alpha & beta tubulin, polymerizing a depolymerizing; movement of and within cells with motors, chromosome segregation, vesicle transport

Explain the function of the motor proteins dynein and kinesin.

Dynein: transports materials going towards cell center

Kinesin: transports going towards cell surface

Identify and describe the three types of cell junctions.

Tight Junction: connect plasma membrane of adjacent cells; no leakage, molecule transport, form barriers; apical (towards outside) and basolateral (on support tissue)

Adheren’s Junction: allow paracellular movement; desmosomes

Communicating Junctions: allow materials to pass from from cytoplasm to cytoplasm; gap junctions (A), plasmodesmata (P)

Explain the differences between the extracellular matrices of plants and animals.

PLANT: meshwork of proteins and polysaccharides to provide support; turgor pressure; composed of middle lamella, primary cell wall, and secondary cell wall.

ANIMAL: mix of fibrous proteins and polysaccharides, present in connective tissue, contains collagen; made from basal lamina, an ECM layer beneath epithelial tissue

Explain the steps in a signal transduction pathway.

1. Receptor activation

2. Signal transduction (often enzyme activation)

3. Response

4. Termination

Identify the four types of signaling.

1. Autocrine: ligand attaches to its own recepter

2. Paracrine: ligand diffuses a short distance to reach its receptor

3. Endocrine: ligand travels through the bloodstream to reach its receptor

4. Juxtracrine: ligand goes through to another cell through membrane contact.

Identify the types of signaling receptors.

Cell Surface Receptors: for polar ligands; integral membrane proteins (outside)

Intracellular Receptors: for nonpolar ligands (inside)

Microfilaments

smallest, actin arranged in a helix; contract, crawl, cytokinesis, vesicle transport, and muscle contraction.

intermediate filaments

animal cell only, intermediate, maintain cell shape and support; function depends on type

Microtubules

largest, made of alpha & beta tubulin, polymerizing a depolymerizing; movement of and within cells with motors, chromosome segregation, vesicle transport

Tight Junction

1. no paracellular leakage

2. molecule transport

3. apical (towards the outside) and basolateral (on support tissue) components

4. form barriers

Adheren’s Junction

1. allows for paracellular movement

2. includes desmosomes

Communicating Junction

1. allows materials to pass from one cell’s cytoplasm to another cell’s cytoplasm.

2. Animal Cell: includes gap junctions in the heart and nerves.

3. Plant Cell: plasmodesmata to pass proteins and RNA.

Basal Lamina

specialized ECM layer beneath epithelial tissues with type IV collagen

Define a plasmid.

circular DNA that replicates independently

Explain the three methods of horizontal gene transfer.

1. Conjugation: cell-to-cell connection

2. Transduction: viral transfer

3. Transformation: uptake of environmental DNA

Differentiate between Gram-positive and Gram-negative bacteria

Gram-positive: blue/purple, thick peptidoglycan walls and no outer membrane

Gram-negative: red/pink, thin peptidoglycan walls and an outer membrane

Identify four differences between bacteria and archaea.

1. Membranes are ester-linked in bacteria, but ether-linked in archaea

2. Bacteria can photosynthesize, but archaea cannot.

3. Histone proteins are present in archaea.

4. Only bacteria are sensitive to antibiotics.

Explain how viruses recognize their host cells.

Viruses recognize their host cells through ligand-receptor interactions.

Define viral capsid and viral envelope.

Viral capsid: genetic material package; genome

Viral envelope: phospholipid that surrounds viruses

Explain how viruses take over other cells to reproduce

1. Attachment

2. Entry

3. Uncoating

4. Replication

5. Assembly

6. Release via lysis or budding

Are viruses life?

No. They cannot independently perform and functions of life, other than evolution.

Explain antigenic drift, antigenic shift, and how they apply to infections like influenza.

Antigenic Drift: accumulation of mutations in genes

Antigenic Shift: recombination that produces novel strains

Influenza has hemagglutinin to assist in its entry, and neuraminidase to assist in its release; if it undergoes antigenic shift, it can produce a new strain.

Identify three conditions necessary for a pandemic.

1. contain a novel combination

2. be able to replicate in humans

3. be efficiently transmitted between humans

Antigenic Drift

accumulation mutation of genes that code for antibodies

Antigenic Shift

recombination of genetic information to create a new strand

Cytolytic

causes host cell death

Cytopathic

causes damage to host cell

What protein assists the influenza virus in its entry?

Hemagglutinin

What protein assists in the release of the influenza virus?

Neuaminidase

Glycine

Nonpolar & increases protein flexibility

Proline

Creates a kink in the polypeptide due to hook in chemical structure

Cysteine

Allows for a disulfide bond to covalently link side chains and form cross bridges.