BIOL 205 Exam #1

Content leading up to exam 1 of BIOL 205

What are the parts of a prokaryotic cell?

Ribosomes, plasmids, chromosomes, cytoplasm, plasma membrane, and cell wall (some but not all).

What is the exoskeleton and its purpose?

A tough, fibrous layer that surrounds the plasma membrane, and protects the shape and rigidity of cells.

What is the cytoskeleton and its purpose?

Maintain cell shape and help with cell division. Actin filaments, intermediate filaments, and microtubules.

What are the external structures on a prokaryotic cell?

Flagella (long filament that rotates to propel cell), fimbriae (neelelike projections used to attach cell)

What is the morphological difference between a eukaryotic cell and a prokaryotic cell?

Eukaryotes have a membrane bound nucleus

What are the different eukaryotic kingdoms?

Protists, fungi, plants, and animals

What are the different prokaryotic kingdoms?

Bacteria and archaea

What is the benefit of organelle compartmentalization?

Deparates incompatible chemical reactions and increases efficiency of compatible chemical reactions.

What is the nucleus and its purpose?

Organized membrane bound compartment surrounded by double latered nuclear envelope with studded pore like openings linked to nuclear lamina. contains nucleolus where ribosomes RNA is synthesized

What are ribosomes and their purpose?

Protein manufacturers that lack a membrane, some are located free in the cytosol and some are attached to the rough ER

What is the enodplasmic reticulum and its purpose?

Rough ER and smooth ER. continuous with the nuclear envelope, membrane enclosed factory that synthesizes additional materials

What is the rough ER and its purpose?

Synthesizes proteins related to membrane function to be shipped to organelles, inserted into the plasma membrane or secreted to the cell exterior

What is the smooth ER and its purpose?

Lacks ribosomes, contains enzymes that catalyze reactions involving lipids that may: synthesize lipids, break down lipids or other toxic molecules

What is the golgi apparatus and its purpose?

Most proteins and lipids pass through here on the way out of the cell. Formed by series of stacked, flat, membranous sacs called cisternae. ‘Cis’ surface faces nucleus, ‘trans’ surface faces plasma membrane.

What are lysosomes and their purpose?

Recycling center found only in animal cells, contain approx. 40 different enzymes.

What are vacuoles and their purpose?

Found in plants fungi and other eukaryotes, take up a lot of volume. Roles include storing water and ions, proteins, digesting/recycling macromolecules.

What are peroxisomes and their purpose?

Globular organelles originating when empty vesicles from ER are loaded with peroxisome-specific enzymes from cytosol. Center of redox reactions.

What is the mitochondria and its purpose?

Supplies ATP to cells. Encased in outer membrane and inner membrane folded into series of sac-like cristae. Contains their own mtDNA and manufactures their own ribosomes.

What are chloroplasts and their purpose?

Where photosynthesis takes place, part of a larger organelle family called plastids. Three membranes: innermost contains flattened sacs called thylakoids, thylakoids arranged in stacks called grana, surrounding thylakoids is the stroma. Manufacures their own ribosomes.

What is endosymbiosis theory?

Mitochondria and chloroplast were once free-living bacteria that were englufed by the ancestor of modern eukaryotes. Supported by the fact that each contain their own DNA, make their own ribosomes, and grow/divide separately to cell division.

How do proteins get trafficked?

Proteins have a zip code that tells the cell where they go.

What is Post-Translational Transport?

Ribosomes make the whole protein in the cytosol. Gets sent to mitochondria, peroxisomes, chloroplasts, and nucleus from cytosol.

What is Co-Translational Transport?

Proteins are transported by the ribosomes as they’re being made from the cytosol to the endoplasmic reticulum.

What is Vesicle Transport?

Proteins transported by part of the membrane from ER and Golgi to cell exterior, plasma membrane, lysosome, other parts of the endomembrane system.

What is the nuclear envelope and its purpose?

Separates the nucleus from the rest of the cell. Perforated with openings called nuclear pore complexes.

How do molecules enter the nucleus?

Nuclear pores serces as gateway, proteins contain 17-amino-acid long nuclear localization signal (NLS) that serces as a molecular address.

What are actin filaments and their purpose?

Smallest cytoskeleton element, made up of actin, bonds to and hydrolyzes ATP. Interacts with motor protein myosin.

What are intermediate filaments and their purpose?

Keratins and nuclear lamins are intermediate filaments. Helps maintain shape of nucleus.

What are mircotubules and their purpose?

Largest cytoskeletal element. Made of tubulin dimers (alpha/beta-tubulin), tubulins bind GTP beta-tubulins hydrolyze GTP. Plus ends grow faster than minus ends. Serve as tracks for vesicle transport using motor proteins kinesin dynein.

What are the flagella and cilia and their purpose?

Flagella are long hairlike projections that move cells. Cilia are shorter/more abundant and help attach the cell. 9 + 2 arrangement of axonemes (9 microtubule pairs surrounded by two central microtubules).

What is condensation?

Covalent bonding of two molecules to form a larger molecule with water formed as a byproduct.

What is hydrolysis?

Splitting of larger molecules into smaller ones, consuming water

What are polysaccharides/carbohydrates?

Play an important role in energy, contribute to cell structure, involved with cell recognition and identity.

What are the roles of carbohydrates?

Monosccharides: glucose

Disaccharides: sucrose and lactose

Polysaccharides: starch, glycogen, cellulose, chitin, peptidoglycan

What are lipids?

Carbon containing compounds, largely nonpolar and hydrophobic.

What are saturated vs unsaturated fatty acids?

Fatty acids are hydrocarbon chains bonded to carboxyl functional groups, assembled into fats and phospholipids. Unsturated fatty acids have kinks in the chains (double C-C bond).

Lipids - Fats

Composed of three fatty acids linked to glycerol via an ester linkage. Primary role is energy storage.

Lipids - Phospholipids

Glycerol linked to a phosphate group bonded to a charged or polar molecule, twohydrocarbon chains. Primary role is to form cell membranes. Amphipathic.

Lipids- Steroids

Distinguished by a bulky, four-ring structure. Differ from each other by attached functional groups.

What is nucelic acid and its parts?

Polymer of nucleotide monomers. Three components: five-carbon sugar, phosphate group and, a nitrogenous base (both bonded to the sugar molecule).

What parts make up the structure of amino acids?

Amino acids make up proteins, composed of a central carbon atom bonded to and H, NH2, COOH, and functional group containing R-group. In water amino group acts as a base, carboxyl group acts as an acid.

How do amino acids polymerize?

They form a covalent peptide bond between the carboxylic carbon and amino group nitrogen.

What are the three key points about peptide-bonded backbone?

1. R-group is oriented outward to interact with each other or water

2. Backbone begins with free carboxyl group (C-terminus) and begins with free amino group (N-terminus)

3. The peptide bond itself cannot rotate

What are the three major chemical categories of R-groups?

Hydrophilic uncharged and charged R-groups. Nonpolar hydrphobic R-groups

How do you determine what type of R-group?

If it’s charged than it’s charged. If it’s not and it contains and oxygen than it’s uncharged polar. If neither then it’s nonpolar.

Describe the four levels of protein organization

1. Primary - polypeptide sequence

2. Secondary - Some stereotypical preliminary folds (alpha-helix twist, beta-pleated sheet)

3. Tertiary - Interaction between R-groups causing bending and folding

4. Quaternary - Two or more polypeptide subunits bonded (homodimers/heterodimers)

What are the five kinds of interactions that can occur in the tertiary structure?

1. Hydrogen bonding

2. Hydrophobic interactions

3. Dipole interactions

4. Covalent bonding (sulfhydryl groups)

5. Ionic bonding (salt bridge)

What are three examples of protein functions?

1. Catalysis (enzymes) - speed up chemical reactions

2. Structure - shape cells and comprise body structures

3. Movement - motor proteins move cells or molecules within cells

What is more stable, folded molecule or unfolded molecule?

Folded molecule is more stable because it has less potential energy.

What is the purpose of a molecular chaperone?

Molecular chaperones can assist misfolded proteins in folding/refolding or deliver them to lysosome/proteasome to be destroyed.

What are two changes that can disrupt the folding of a protein?

Environmental changes such as temperature and pH changes.

What is the purpose of enzymes?

1. They lower the energy barrier for a reaction (catalyst)

2. Hold substrates in precise orientation

3. Have an active site where substrates can bind and react with key amino acid R-groups

What is a cofactor?

An umbrella term for metal ions that reversibly interact with enzymes

What is a coenzyme?

A subset of cofactors consisting of non-protein organic molecules that are frequently modified by the enzymatic reaction.