Cell Biology Exam 1 Study Guide

Question 1

1:What is the basic unit of biology? What are cells constantly doing?

Answer 1

cells; constantly changing: grow, reproduce, become specialized

Question 2

1: What is the Cell Theory?

Answer 2

all organisms consist on 1 or more cells; the cell is the basic unit structure for all organisms; all cells arise only from preexisting cells

Question 3

1: What 3 strands of Biology are weaved into Modern Cell Biology: In general, what is the focus of each strand and how do they contribute to the understanding of cell biology?

Answer 3

Cytology: focuses mainly on cellular structure and emphasizes optical techniques; Biochemistry: focuses on cellular structure and function; Genetics: focuses on information flow and heredity and includes sequencing of the entire genome (all of the DNA) in numerous organisms

Question 4

1: What are the different types of Microscopy and what makes them stand apart from each other in terms of how they help cytology studies? (Light microscopy)

Answer 4

Light microscopy: earliest tool, identifies nuclei, mitochondria, chloroplast, also called bright field microscopy because white light passes directly through a specimen, limit of resolution; Phase-contranst and DIC microscopy: make it possible to see living cells clearly, phase of transmitted light changes as it passes through a structure with different density from the surrounding medium, enhance and amplify slight changes; Fluorescence microscopy: allows detection of proteins, DNA sequences, or molecules that have been made fluorescent by binding to antibodies, antibody can be coupled to fluorescent molecule which emits fluorescence, GFP can be used to study temporal and spatial distribution of proteins; Confocal: use laser beam to illuminate single plane of fluorescently labeled specimen; Digital video: use video camera to collect digital images

Question 5

1: What are the different types of Microscopy and what makes them stand apart from each other in terms of how they help cytology studies? (Electron Microscopy)

Answer 5

Electron microscope: use beam of electrons rather than light, limit of resolution about 100 times better than light microscope, magnification is much higher up to 100,000x; Transmission electron: electrons transmitted though the specimen; Scanning electron: surface of specimen is scanned by detecting electrons deflected from outer surface; All this allowed for visualization of specimen in 3-D and allows visualization of individual atoms

Question 6

1:What is the domga of molecular biology?

Answer 6

DNA replication -> DNA -> Transcription -> RNA -> Translation -> Protein

Question 7

1:How do we design a good experiment as researchers and scientists

Answer 7

One condition is varied- independent variable, all other variables are kept constant, the outcome is dependent variable; in vivo- involve living organisms; In vitro- done outside of living organisms; In-silico- done in computers

Question 8

4: Why would the cell create membrane bound organelles

Answer 8

eukaryotic cell has a true, membrane-bounded nucleus which holds the DNA

Question 9

4: Know the general roles of the cell organelles (Plasma membrane, nucleus, Endomembrane system, Er, RER, SER, Golgi, Secretory vesicles)

Answer 9

Plasma membrane- surrounds every cell, make sure cell contents are retained, holds lipids, membrane proteins, lipid bilayer with phospholipid molecule:2 hydrophobic tails 1 hydrophillic head amphipathic molecule; nucleus: holds the DNA surrounded by nuclear envelope with in and out membranes also has pores which is a transport channel; Endomembrane System- Er: has cisternae-tubes, lumen- space, RER- ribosomes on it that synthesize polypeptides, free ribosomes not associated with ER, SER- no role in protein synthesis, involved syntheis of lipids and steroids- cholesterol, inactivate and detoxify harmful stuff; Golgi apparatus: cisternae-vesicles, processing packaging secretory proteins, synthesis of complex polysaccharides, takes transition vesicles from ER then modifies and process the contents in the Golgi complex, then the contents move to other parts of the cell through the vesicles; Secretory vesicles: Materials exported from the cell packaged into secretory vesicles then move to plasma membrane, fuse with it releasing their contents outside of the cell (exocytosis)

Question 10

4: Know the general role of the cell organelles (Mitochondria, Chloroplasts)

Answer 10

Mitochondria: energy production, degradation of sugars, aerobic respiration, in and out mitochondrial membrane contain hundreds of mitochondria and the in encloses the matric with semifluid, matrix holds DNA molecules, contain enzymes and intermediates for oxidation of sugars and ATP found on cristae, infoldings of mitochondrial membrane, Chloroplast and mitochondria: semiautonomous organells, similar to bacteria in size and shape and double membrane; DNA, mRNA, tRNA, rRNA sequences, ribosome size, inhibitros of RNA and protein synthesis, protein factors used in protein synthesis and ribosomes, endosymbiont theory proposes mitochondria and chloroplast originated from ancient bacteria; Chloroplasts: energy production of the cells, harvest solar energy and converts it to chemical energy in ATP, site of photosynthesis large and numerous in green plants, has inner and outer membranes, third membrane system called thylakoids connected by stroma thylakods stacked into grana

Question 11

4: Know the general role of the cell organelles (Lysosome, Peroxisome, Vacuoles, Ribosomes, Cytoskeleton, ECM)

Answer 11

Lysosomes: synthesized on RER, transported to Golgi, packaged in vesicles, become lysosomes, hydrolases prevent them from digesting contents of cell, has a glycosylated covering that protect membrane and cell, can break down biological molecules; Peroxisomes: single membrane, prominent in liver and kidney cells, highly toxic to cells formed into water and oxygen by catalase, protected from peroxide, in animals they breakdown fatty acids that mitochondria are too slow to do; Vacuoles: membrane bounded, temporary storage or transport, Phagocytosis-ingestion form environment, formation of phagosome, fuses with lysosomes contents are hydrolyzed to provide nutrients to cell, In plants they are central vacuole maintain turgor pressure; Ribosomes: site of protein synthesis, seen under electron microscope, own type of rRNA, numerous, found in mitochondria and chloroplast similar in size and composition in bacteria; Cytoskeleton: gives cell its shape and internal organization, cell movement and cell division, framework for positioning and moving organelles and macro molecules in cell, Microtubules, Microfilaments, Intermediate filaments, Septins found in animal and fungi not plants; ECM: extracellular matrix-animals gives physical support to cells, cell wall-bacteria, archaea plant, fungal, cell motility and migration, cell division cell recognition and adhesion, differentiation during embryonic development, animals- junctions connecting nearby cells, plant-plasmodesta-space between cell wall of plants for communication and exchange

Question 12

4: Difference in bacteria, animal and plant cells

Answer 12

Bacteria: prokaryotes nonnucleated, genetic info in nucleoid and present in cell as a chromosome, compartmentalize activities; Animal: eukaryotes, no cell wall but extracellular matrix, peroxisomes, vacuoles are temporary storage and transport, septins; Plants: eukaryotes, photosynthesis occurs, lots of chloroplast , plasmodesmata for communication and exhange

Question 13

2: What are the 5 Principles to cell biology:

Answer 13

Characteristics of carbon, characteristics of water, selectively permeable membranes, synthesis of polymerization of small molecules, Self-assembly

Question 14

2: Why is carbon so important to the study of cell biology?

Answer 14

Molecules of importantance to the cell biologist have a backbone or skeleton, or carbon atoms linked together covalently in chains or rings

Question 15

2: What kinds of bonds of carbon usually form in biological molecules?

Answer 15

Carbon atoms usually form covalent bonds with other carbon atoms and with oxygen, hydrogen, nitrogen, and sulfur

Question 16

2: What are hydrocarbon and why are they important?

Answer 16

Hydrocarbons are chains or rings composed of only carbon and hydrogen; play a role in the structure of biological membranes; the interior of each bio membrane in non aqueous environment consisting of the long hydrocarbon tails of phospholipid molecules; the hydrocarbon tail project into the interior of the membrane form either surface

Question 17

2: What are Biological Compounds normally made of?

Answer 17

contain carbon, hydrogen and one or more atoms of oxygen as well as nitrogen, phosphorus or sulfur; usually part of functional groups; functional groups are common arrangements of atoms that confer specific chemical properties on a molecules

Question 18

2: Know the different Chemical Bonds

Answer 18

Study Table

Question 19

2: Why is water important?

Answer 19

Water has an indispensable role for life as it is the universal solvent in bio systems, its polarity is able to dissolve a large variety of substances

Question 20

2: What characteristics of water accounts for water’s properties? Why are those properties important?

Answer 20

polarity most important which accounts for water’s, cohesiveness, temperature-stabilizing capacity, solvent properties; unequal distribution of electrons gives water its polarity; the oxygen atom at one end is highly electronegative drawing electrons toward it, this results in partial negative charge at this end of the molecule and partial positive charge around hydrogen atoms; Water molecules attracted to each other due to polarity and associate together through hydrogen bonds: electronegative oxygen of one molecule is associated with electropositive hydrogens of nearby molecules, extensive network of hydrogen-bonded molecules make water cohesive: surface tension, boiling point, specific heat, heat of vaporization; high specific heat gives water its temperature stabilizing capacity so that water changes temperature slowly protecting living systems from extreme temperature changes, without this energy released in cell metabolism would cause cells to overheat and die

Question 21

2: What do the terms solute, solvent, hydrophobic, and hydrophillic stand for?

Answer 21

Hydrophobic: tendency of nonpolar groups within a macromolecule to associate with each other to minimize their contact with water water fearing; Hydrophillic: water loving; solute: substance that is dissolved in solvent; Solvent: fluid in which another substance can dissolve

Question 22

2: Key characteristics of membranes?

Answer 22

The cellular membrane is hydrophobic permeability barrier, consist of phospholipids, glycolipids, and membranes proteins, membrane lipids are amphipathic both hydrophobic and hydrophilic regions, amphipathic phospholipids have a polar head, the polarity is due to a negatively charged phosphate group linked to a positively charged group, the polar heads of membrane phospholipids face outward toward the aqueous environment, they also have 2 nonpolar hydrocarbon tails, they hydrophobic tails are oriented inward, the resulting structure is the lipid bilayer, because of the hydrophobic interior a lipid bilyaer is readily permeable to nonpolar molecules, however it is quite impermeable to most polar molecules and highly impermeable to all ions, biological membranes are selectively permeable

Question 23

3: Know the macromolecules of the cell , monomers, key enzymes, and the bonds to maintain macromolecules? Make a table

Answer 23

Make a table; proteins nucleic acids and polysaccharides, lipids share some features of macromolecules but are synthesized somewhat differently

Question 24

3: What key reactions create and degrade macromolecules?

Answer 24

Activated monomers react with one another in condensation reaction (removal of water molecule), degradation of polymers occurs via hydrolysis, breaking the bond between monomers through addition of 1 H+ and 1 OH- (addition of water molecule)

Question 25

3: Key features of macromolecules (Polysaccharides)

Answer 25

long chain polymers of sugars and sugar derivatives, repeating units of poly are monosaccharides, they serve primarily in structure and storage, short polymers oligosaccharides are sometimes attached to cell surface proteins, most common mono is glucose, poly can be stored and can provide structure; Storage: glycogen in animals, fungi and bacteria, starch in plants; Structural: Cellulose in plants, Chitin in insect exoskeleton, crustacean shells, and fungal cell walls

Question 26

3: Key Features of macromolecules (Lipids)

Answer 26

all have hydrophobic nature with little affinity for water, some are amphiphatic having polar and nonpolar regions, functions include energy storage membrane structure, specific biological functions, signal transmission, can be divided into classes based on their structure; Fatty acids- building blocks of several classes of lipids, long amphipathic unbranched hydrocarbon chain with carboxyl group at one end. Polar carboxyl group is head and nonpolar hydrocarbon chain is the tail. Saturated fatty acids- each carbon atom in the chain is bonded to the maximum number of hydrogens, Unsaturated - have one or more double bonds so they have bends in the chains are are less tightly packed, Tricylglycerols- energy storage; Phospholipids- important to membrane structure cuz of their amphipathic nature, phosphoglycerides most predominant in membranes, length and degree of saturation of the fatty acids have profound effect on membrane fluidity; Sphingolipids are found in outer leaflet of plasma membrane bilayer structural function and believed to protect the cell surface from harmful environmental factors, important in communication between cell and external environment; Glycolipids- has a carbohydrate instead of a phospholipid, occur largely on the outer monolayer of plasma membrane; Steroids: derivatives of a four-ringed hydrocarbon skeleton which distinguishes them from other lipids: Cholesterol is the starting material for synthesis of steroid hormones, insoluble and found in plasma membrane of animal cells and most membrane organelles; Steroid hormones: sex hormones estrogen in ovaries for females and androgen in male testes

Question 27

3: Key features of macromolecules? (Proteins)

Answer 27

important to macromolecules in all organisms, 9 major classes: enzymes serve as catalysts increasing the rates of chemical reactions, structural proteins- physical support and shape, motility proteins- contraction and movement, regulator proteins- control and coordinate cell function, transport proteins- move substances in and out of cells, signaling proteins- communication between cells, receptor proteins- enable cells to respond to chemical stimuli from the environment, defensive proteins-protect against disease, storage proteins- resevoirs of amino acids

Question 28

3: Key features of macromolecules (amino acids)

Answer 28

20 kinds of amino acids used in protein synthesis, no proteins have the same amino acid sequence, amino acid structure: alpha carbon attached to amino group, carboxyl group, and variable side chain (r group), each has r group- unique side chain, specific properties of amino acids depend on the nature of their R groups, amino acids are linked through peptide bond, peptide bond is covalent C-N bond, polypeptide have directionality (polarity), end with amino group called N- or amino terminus, end with carboxyl group called C- or carboxyl terminus; immediate product of amino acid polymerization is polypeptide, polypeptide doesn’t become a protein until it is unique, stable, 3-D shape and is biologically active, monomeric proteins- single polypeptide are, multimeric proteins -2 or more polypeptides

Question 29

3: Key features of macromolecules (bonds and interactions)

Answer 29

for protein to adopt conformation it needs: covalent bonds- covalent disulfide bonds form between the sulfur atoms of 2 cysteine residues, Noncovalent interactions- ionic: between aa side chains and other aa or molecules, hydrogen: between aa and other aa or molecules (water), van der waals- weak non-covalent interactions between nonpolar molecules, hydrophobic- nonpolar aa will associate with each other to avoid interaction with aqueous solutions, these bonds and interactions are required for polypeptides to form multimeric proteins, the overall 3D structure of a protein is determined by the interactions of R-groups, chaperones facilitate protein folding

Question 30

3: Key features of macromolecules (Protein Structure)

Answer 30

shape and structure of protein described in 4 levels of organization, Primary structure- amino acid sequence, covalent peptide bonds, written from N-terminus to C-terminus, specifies the order of nucleotides in the corresponding messenger RNA, order and identity of amino acids directs the formation of the higher order structures; Secondary structure- local folding of polypeptide- local regions structure result from hydrogen bonding between NH and CO groups along polypeptide backbone, H bonds form a helixs -coils and b sheets- arrow head point s at C-terminus, region that forms b-sheet interact 2 ways: parallel b sheet: 2 interacting regions run in same N-terminus to C-terminus, antiparallel- run 2 strands in N-terminus to C-terminus directions; Motifs are secondary structure stretches of a helices and/or b sheets, when same motif is present in different proteins it usually serves same purpose; Tertiary structure: 3-D conformation, reflects unique aspect of the amino acid sequence depends on interactions of the R group, results from sum of hydrophobic residues avoiding water, hydrophilic residues interacting with water, repulsion of similarly charged residues, attraction between oppositely charged residues, domain is discrete folded tertiary structure with specific function, proteins with similar functions usually have separate domain for each function; Quaternary structure: interactions between monomeric proteins to form a multimeric unit, follows boding as tertiary, the term applies specifically to multimeric proteins

Question 31

3: Key features of macromolecules (Nucleic Acids, Primary function of genetic material, DNA vs RNA)

Answer 31

nucleic acids: important to cell because they store transmit and express genetic info, they are linear polymers of nucleotides, DNA is deoxyribonucleic acids and RNA ribonucleic acid; Primary function of genetic materials: storage of genetic info- instruction for all characteristics of a cell, replication and inheritance- info for synthesis of genetic material to be transmitted to daughter cells, Expression of genetic message- directions for cell activity; DNA vs RNA: differ chemically in their role in the cell, DNA contain 5-carbon deoxyribose, serves as repository of genetic info, RNA 5-carbon sugar ribose, several roles in expressing DNA’s info

Question 32

3: Key Features of macromolecules (Monomers are nucleotides, The polymers are DNA and RNA, Complementary Base Pairing)

Answer 32

RNA and DNA consist of only 4 different nucleotides, each nucleotides have 5-carbon sugar, phosphate group attached to C-5 of sugar, N-containing aromatic base attached to C1 of the sugar; Polymers: nucleic acids are linear polymers of nucleotides, linked by covalent phosphodiester bond between C-d phosphate of sugar and C-3 OH of the next sugar of nucleotides, Phosphate sugar backbone nucleotide sequences are conventionally written in 5’ to 3’ direction, polarity is 5’ to 3’ the two strands held together by hydrogen bonding between purine-pyrimidine base on opposite strands; Complementary base pairing: template is preexisting molecule used to ensure that new nucleotides (NTPs for RNA, dNTPs for DNA) are added in the correct order and correct base pairing between the template and the incoming nucleotide is required to specify correct order allows: A to form two hydrogen bonds with T, G to form three hydrogen bonds with C, This base pairing is a fundamental property of nucleic acids, form the double DNA helix the strands need to be antiparallel (5 to 3 and 3 to 5) and complementary (base pairing), RNA is normally single stranded, but can form secondary structures that also depends on base pairing

Question 33

3: Key features of macromolecules (Hereditary info)

Answer 33

Genes consist of DNA that codes for functional products that are usually protein chains, The information in a cell’s DNA molecules undergoes replication to generate two copies for distribution into each daughter cell, Instructions stored in DNA are transmitted in a two-stage process called transcription and translation, Transcription: RNA is synthesized in an enzymatic reaction that copies information from DNA, Translation: the base sequence of RNA is used to direct the synthesis of a polypeptide (protein)