Exam 2 Review Slides Lectures 5-8 Ch. 2 (pp ), Ch. 3 and Ch. 9 (pp )

2 Cell Membranes Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

3 Passage of Materials through the Cell Membrane oxygen, carbon dioxide and other lipid-soluble substances diffuse freely through the membrane Carrier/channel proteins required for all but fat- soluble molecules and small uncharged molecules

4 Lecture Review TRANSPORT PROCESS IS ENERGY NEEDED? CONCEN- TRATION GRADIENT GENERAL DESCRIPTION EXAMPLE IN HUMANS SIGNIFICANCE SIMPLE DIFFUSION NO[HIGH] TO [LOW] spreading out of molecules to equilibrium O 2 into cells; CO 2 out of cells. Cellular Respiration FACILITATED DIFFUSION NO[HIGH] TO [LOW] Using a special cm carrier protein to move something through the cell membrane (cm) Process by which glucose enters cells OSMOSISNO[HIGH] TO [LOW] water moving through the cm to dilute a solute maintenance of osmotic pressure. Same FILTRATIONNO[HIGH] TO [LOW] using pressure to push something through a cm (sprinkler hose) manner in which the kidney filters things from blood removal of metabolic wastes ACTIVE TRANSPORT YES[LOW] TO [HIGH] opposite of diffusion at the expense of energy K + -Na + -ATPase pump maintenance of the resting membrane potential

5 Osmotic Pressure/Tonicity Osmotic Pressure (Osmolarity) – ability of solute to generate enough pressure to move a volume of water by osmosis *Osmotic pressure increases as the number of nonpermeable solutes particles increases isotonic – same osmotic pressure as a second solution hypertonic – higher osmotic pressure hyp O tonic – lower osmotic pressure 0.9% NaCl 5.0% Glucose Crenation The O in hyp o tonic

6 Lecture Review TRANSPORT PROCESS IS ENERGY NEEDED? CONCEN- TRATION GRADIENT GENERAL DESCRIPTION EXAMPLE IN HUMANS SIGNIFICANCE ACTIVE TRANSPORT YES[LOW] TO [HIGH] opposite of diffusion at the expense of energy K + -Na + -ATPase pump maintenance of the resting membrane potential ENDOCYTOSISYES[LOW] TO [HIGH] bringing a substance into the cell that is too large to enter by any of the above ways; Phagocytosi: cell eating; Pinocytosis: cell drinking. Phagocytosed (foreign) particles fuse with lysosomes to be destroyed help fight infection EXOCYTOSISYES[LOW] TO [HIGH] expelling a substance from the cell into ECF Exporting proteins; dumping waste Same

7 Cellular Organelles CELL COMPONENTDESCRIPTION/ STRUCTURE FUNCTION(S) CELL MEMBRANEBilayer of phospholipids with proteins dispersed throughout cell boundary; selectively permeable (i.e. controls what enters and leaves the cell; membrane transport) CYTOPLASMjelly-like fluid (70% water)suspends organelles in cell NUCLEUSCentral control center of cell; bound by lipid bilayer membrane; contains chromatin (loosely colied DNA and proteins) controls all cellular activity by directing protein synthesis (i.e. instructing the cell what proteins/enzymes to make. NUCLEOLUSdense spherical body(ies) within nucleus; RNA & protein Ribosome synthesis RIBOSOMESRNA & protein; dispersed throughout cytoplasm or studded on ER protein synthesis ROUGH ERMembranous network studded with ribosomes protein synthesis SMOOTH ERMembranous network lacking ribosomes lipid & cholesterol synthesis GOLGI“Stack of Pancakes”; cisternaemodification, transport, and packaging of proteins Table 1 of 2

8 Cellular Organelles CELL COMPONENTDESCRIPTION/ STRUCTURE FUNCTION(S) LYSOSOMESMembranous sac of digestive enzymesdestruction of worn cell parts (“autolysis) and foreign particles PEROXISOMESMembranous sacs filled with oxidase enzymes (catalase) detoxification of harmful substances (i.e. ethanol, drugs, etc.) MITOCHONDRIAKidney shaped organelles whose inner membrane is folded into “cristae”. Site of Cellular Respiration; “Powerhouse of Cell” FLAGELLAlong, tail-like extension; human spermlocomotion CILIAshort, eyelash extensions; human trachea & fallopian tube to allow for passage of substances through passageways MICROVILLImicroscopic ruffling of cell membraneincrease surface area CENTRIOLESpaired cylinders of microtubules at right angles near nucleus aid in chromosome movement during mitosis Table 2 of 2

9 A Closer Look at Mitochondria Strategically placed in cell where ATP demand is high Concentration of enzymes in the matrix is so high that there is virtually no hydrating water. Enzyme-linked reactions and pathways are so crowded that normal rules of diffusion do not apply! Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001 (Impermeable to charged or polar molecules)

PLEASE SIGN IN Sign in sheet is on the table in the BACK of the room by the coat rack on the same side of the room as the projection screen Exam Review slides are the same ones distributed Tuesday (I put them there in case you didn’t pick up a set) 10

11 Overview of Cellular Respiration Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001 Cellular respiration (aerobic) Anaerobic ATP *Most ATP from here ATP

12 Cell Nucleus control center of cell nuclear envelope (membrane) porous double membrane separates nucleoplasm from cytoplasm (*eukaryotes only) nucleolus dense collection of RNA and proteins site of ribosome production chromatin fibers of DNA and proteins stores information for synthesis of proteins Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9 th ed., Pearson

The Cell Cycle series of changes a cell undergoes from the time it forms until the time it divides stages interphase mitosis cytoplasmic division differentiation Differentiated cells may spend all their time in ‘G 0 ’ (neurons, skeletal muscle, red blood cells). Stem cells may never enter G 0 Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9 th ed., Pearson

The Cell Cycle Must Have Controls If DNA is damaged, cell must NOT be allowed to enter mitosis DNA must be completely replicated before mitosis takes place At metaphase, the chromosomes must be correctly positioned at the spindle fiber equator Each phase of the cell cycle must be completed before the next is begun DNA/Cell replication must not proceed unless a ‘signal to proceed’ is received

Why the Cell Cycle Must Have Controls 1. DNA/Cell replication must not proceed unless a ‘signal to proceed’ is received 2. DNA must be completely and correctly replicate before mitosis takes place otherwise it should not occur. 3. Chromosomes must be correctly positioned during mitosis so they are separated correctly Major points summarized…same as lecture 6 slide

What are the Controls of the Cell Cycle? cell division capacities vary greatly among cell types skin and bone marrow cells divide often liver cells divide a specific number of times then cease chromosome tips (telomeres) that shorten with each mitosis provide a mitotic clock (cell senescence) cells divide to provide a more favorable surface area to volume relationship growth factors and hormones stimulate cell division hormones stimulate mitosis of smooth muscle cells in uterus epidermal growth factor stimulates growth of new skin tumors are the consequence of a loss of cell cycle control contact inhibition Cyclins and Cyclin-dependent kinases provide central control

17 Mitosis and Meiosis Figures from: Martini, Anatomy & Physiology, Prentice Hall, 2001 Mitosis – production of two identical diploid daughter cells Meiosis – production of four genetically varied, haploid gametes

The Cell Cycle and Mitosis INNKEEPER (INTERPHASE) POUR (PROPHASE) ME (METAPHASE) ANOTHER (ANAPHASE) TEQUILA (TELOPHASE/CYTOKINESIS)

Interphase Cell Figure from: Hole’s Human A&P, 12 th edition, 2010

Prophase What structure joins the sister chromatids together? Figure from: Hole’s Human A&P, 12 th edition, 2010

Metaphase Figure from: Hole’s Human A&P, 12 th edition, 2010

Anaphase Figure from: Hole’s Human A&P, 12 th edition, 2010

Telophase (and Cytokinesis)

24 Cell Death Two mechanisms of cell death –Necrosis –Programmed cell death (PCD or apoptosis) Necrosis –Tissue degeneration following cellular injury or destruction –Cellular contents released into the environment causing an inflammatory response Programmed Cell Death (Apoptosis) –Orderly, contained cell disintegration –Cellular contents are contained and cell is immediately phagocytosed

25 Stem and Progenitor Cells Stem cell can divide to form two new stem cells can divide to form a stem cell and a progenitor cell totipotent – can give rise to any cell type (Embryonic stem cells) pluripotent – can give rise to a restricted number of cell types Progenitor cell committed cell further along differentiation pathway can divide to become any of a restricted number of cells pluripotent *not self-renewing, like stem cells Same as lecture 6 slide

26 Stem and Progenitor Cells Stem cell can divide to form two new stem cells can divide to form a stem cell and a progenitor cell totipotent – can give rise to any cell type (Embryonic stem cells) pluripotent – can give rise to a restricted number of cell types Progenitor cell committed cell can divide to become any of a restricted number of cells pluripotent

27 Some Definitions… Gene – segment of DNA that codes for a protein or RNA - About 30,000 protein-encoding genes in humans - DNA’s instructions are ultimately responsible for the ability of the cell to make ALL its components *Chromatin – combination of DNA plus histone proteins used to pack DNA in the cell nucleus Genome – complete set of genes of an organism - Human Genome Project was complete in Genomes of other organisms are important also Genetic Code – method used to translate a sequence of nucleotides of DNA into a sequence of amino acids

28 Structure of Nucleic Acids Figure from: Alberts et al., Essential Cell Biology, Garland Press, 1998 Purines: Adenine and Guanine (double ring) Pyrimidines: Cytosine, Thymine, and Uracil (single ring)

29 Structure of DNA A double-stranded DNA molecule is created by BASE- PAIRING of the nitrogenous bases via HYDROGEN bonds. Notice the orientation of the sugars on each stand. *DNA is an antiparallel, double-stranded polynucleotide helix 5' 3' 5' 3'

30 Structure of DNA Base pairing in DNA is VERY specific. - Adenine only pairs with Thymine (A-T) - Guanine only pairs with Cytosine (G-C) Note that there are: - THREE hydrogen bonds in G-C pairs - TWO hydrogen bonds in A-T pairs - A purine (two rings)base hydrogen bonds with a pyrimidine base (one ring) Figure from: Martini, “Human Anatomy & Physiology”, Prentice Hall, 2001 Complementary base pairing…

31 DNA Replication Figure from: Martini, “Human Anatomy & Physiology”, Prentice Hall, 2001 THINGS TO NOTE: 1.DNA is replicated in the S phase of the cell cycle 2.New strands are synthesized in a 5’ to 3’ direction 3.DNA polymerase has a proofreading function (1 mistake in 10 9 nucleotides copied!) 4.Semi-conservative replication describes pairing of post- replication strands of DNA (1 new, 1 old) 5’ 3’ 5’ 3’

32 RNA RNA is a polynucleotide with important differences from DNA –Uses Uracil (U) rather than Thymine (T) –Uses the pentose sugar, ribose –Usually single-stranded There are three important types of RNA –mRNA (carries code for proteins) –tRNA (the adapter for translation) –rRNA (forms ribosomes, for protein synthesis)

33 Transciption/Translation Transcription –generates mRNA from DNA –Occurs in nucleus of the cell –Uses ribonucleotides to synthesize mRNA Translation –generates polypeptides (proteins) from mRNA –Occurs in the cytoplasm of the cell –Uses 3 components: mRNA, tRNA w/aa, and ribosomes

34 The Genetic Code 1.Codon – group of three ribonucleotides found in mRNA that specifies an aa 2.Anticodon – group of three ribonucleotides found in tRNA that allows specific hydrogen bonding with mRNA 3.AUG is a start codon and also codes for MET. UAA, UAG, and UGA are stop codons that terminate the translation of the mRNA strand.

Find the AMINO ACID SEQUENCE that corresponds to the following gene region on the DNA: Template -> C T A A G T A C T Coding -> G A T T C A T G A

36 tRNAs Transfer RNAs (tRNA) function as ‘adapters’ to allow instructions in the form of nucleic acid to be converted to amino acids. Figures from: Martini, Anatomy & Physiology, Prentice Hall, 2001

37 Eukaryotic Genes Figure from: Alberts et al., Essential Cell Biology, Garland Publishing, 1998 The template strand of DNA is the one that’s transcribed. The coding strand of DNA is used as the complementary strand for the template strand in DNA and looks like the codons.

38 Eukaryotic mRNA Modification Figure from: Alberts et al., Essential Cell Biology, Garland Publishing, 1998 Newly made eukaryotic mRNA molecules (primary transcripts) undergo modification in the nucleus prior to being exported to the cytoplasm. 1. Introns removed 2. 5' guanine cap added 3. Poly-A tail added

39 The Fate of Proteins in the Cell Breakdown of proteins regulates the amount of a given protein that exists at any time. Each protein has unique lifetime, but the lifetimes of different proteins varies tremendously. Proteins with short life-spans, that are misfolded, or that become oxidized must be destroyed and recycled by the cell. Enzymes that degrade proteins are called proteases. They are hydrolytic enzymes. Most large cytosolic proteins in eukaryotes are degraded by enzyme complexes called proteasomes.

40 Enzymes Enzymes are biological catalysts –Highly specific for their substrate –Lower activation energy needed to start a reaction –Are not consumed during reaction –May require cofactors/coenzymes –Effectiveness is greatly affected by temperature, pH, and the presence of required cofactors Cofactors make some enzymes active ions or coenzymes Coenzymes complex organic molecules that act as cofactors (so coenzymes ARE cofactors) vitamins NAD +

41 GLYCOLYSISTCAETC Where it takes place CytoplasmMitochondria Products ProducedATP NADH Pyruvate ATP NADH,FADH 2 CO 2 ATP NAD+,FAD H 2 O PurposeBreakdown of glucose (6 carbons) to 2 molecules of pyruvate (3 carbons) Generation of energy intermediates (NADH, FADH 2, ATP) and CO 2 Generation of ATP and reduction of O 2 to H 2 O (Recall that reduction is the addition of electrons) What goes on1. Glucose is converted to pyruvate, which is converted to acetyl CoA when there is sufficient O2 present. 2. Acetyl CoA enters the TCA cycle. 3. If O 2 is not present, pyruvate is converted to lactic acid to replenish the supply of NAD + so glycolysis can continue to make ATP 1. The energy in acetyl CoA is trapped in activated carriers of electrons (NADH, FADH 2 ) and activated carriers of phosphate groups (ATP). 2. The carries of electrons that trap the energy from acetyl CoA bring their high energy electrons to the electron transport chain. 1. Chemiosmosis (oxidative phosphorylation) uses the electrons donated by NADH and FADH 2 to eject H + from the matrix of the mitochondria to the intermembrane space. 2. These H + then flow down their concentration gradient through a protein (ATP synthase) that makes ATP from ADP and phosphate. 3. During this process, the H + that come through the channel in ATP synthase are combined with O 2 to make H 2 O. Summary Table of Cell Respiration