M2 Lecture 15,18, part of 20

Question 1

• What are some functions/roles of actively dividing cells?

Answer 1

o Increasing population of single-celled organism
o Growth of multicellular tissue
o Asexual reproduction + replacement of cells lost to wear and tear

Question 2

7.2 The Cell Cycle in Prokaryotic Organisms

In the 3-period cycle newly formed prok. Cell must:

Answer 2

 Increase in size
 Replicate circular chromosome
 Move each of two daughter chromosomes into progeny cell during cell division

Question 3

7.2 The Cell Cycle in Prokaryotic Organisms

What is binary fission?

Answer 3

: division into two parts

Question 4

7.2 The Cell Cycle in Prokaryotic Organisms

Exlapin the 3 periods of the 3 period cell cycle:

Answer 4

o B period:
 Daughter cells are formed, they grow during B period, initiate DNA synthesis
 When nutrients = abundant, prokaryotic cells = no need for B period (b/c can grow quickly enough for it to divide cytoplasm as soon as DNA replication is complete + chromosomes are separated
o C period:
 Once chromosomes = replicated, they separate to opposite ends of cell (poles)
o D period:
 Membrane pinches together between them and 2 daughter cells are formed via binary fission

Question 5

7. 2 a Replication occupies most of the cell cycle in rapidly dividing prokaryotic cells
   - Bacteria + Archaea: use DNA as what?

Answer 5

… as hereditary info then packaged into circular chromosome

Question 6

7.2 a Replication occupies most of the cell cycle in rapidly dividing prokaryotic cells

Where are chromosomes located, what are they?

Answer 6

o Compacted in central region called nucleoid

• A chromosome is a long DNA molecule with part or all of the genetic material of an organism.

Question 7

7. 2 b Replicated chromosomes are distributed actively to the daughter cells in binary fission
   - Bacterial chromosomes separate ____ to membrane dynamics and is linked to DNA replication

Answer 7

independantly

Question 8

7.2 b Replicated chromosomes are distributed actively to the daughter cells in binary fission

What is the Origin of replication (ori)?

Answer 8

o specific region in middle of cell where replication of bacterial chromosomes begins @ specific region of DNA sequence

Question 9

7.2 b Replicated chromosomes are distributed actively to the daughter cells in binary fission

Where is Ori located?

Answer 9

o Ori = located where enzymes for DNA replicated are located

Question 10

7.2 b Replicated chromosomes are distributed actively to the daughter cells in binary fission

o Completion of ori duplication results in what happening?

Answer 10

two new origins migrate towards opposite poles while replication continues for rest of chromosome

Question 11

7.2 b Replicated chromosomes are distributed actively to the daughter cells in binary fission

o Division of cytoplasm is accomplished by what?

Answer 11

Inward constriction of ring of cytoskeleton proteins

Question 12

7.2 c Mitosis has evolved from an early form of binary fission

Is Prokaryotic mechanism of cell division effective? If so, why?

Answer 12

o b/c most prokaryotic organisms have single chromosome

 Means: daughter cell receiving minimum one copy of chromosome= genetic information = complete

Question 13

7.2 c Mitosis has evolved from an early form of binary fission

Is Eukaryotic mechanism of cell division effective? Why or why not?

Answer 13

o b/c genetic info = divided amongst linear chromosomes, each chromosome has much greater length of DNA
o Daughter cell fails to receive a copy of chromosomes = lethal
o Most of cell cycle eukaryotic chromosomes = contained within nuclear membrane

Question 14

7.2 c Mitosis has evolved from an early form of binary fission

o Bacteria + archaea have (an or no?) internal membrane around nucleoid

What does this mean for the organisms?

Answer 14

require different cellular and chromosomal machinery for distributing chromosomes to daughter cells (mitosis)

Question 15

7.2 c Mitosis has evolved from an early form of binary fission
What is the evolutionary advancement of binary fission?

How does this benefit the cell?

Answer 15

• Evolutionary advancement: ability to hold two newly created molecules of double-stranded DNA (chromatids) following DNA synthesis

o Enables cells to keep track of chromosomes and orient them relative to cytoskeleton and ensure distribution to daughter cells

Question 16

7.2 c Mitosis has evolved from an early form of binary fission

• Main components of cytoskeleton (are/aren’t?) present in ancestral prokaryotic cells, there (is/isn’t?) evolution

Answer 16

are, is

Question 17

7.2 c Mitosis has evolved from an early form of binary fission

in higher eukaryotes what happens to the nuclear membrane at time when chromosomes are distributed

Answer 17

it disintegrates and reforms around daughter cells

Question 18

7.2 c Mitosis has evolved from an early form of binary fission
What does variation in miotic apparatus result in?

What is a miotic apparatus?

Answer 18

evolution

a temporary structure in a dividing cell that enables the chromosomes to move to the poles of the cell

Question 19

7. 3 Mitosis and the eukaryotic cell cycle

- Eukaryotes require what to be genetic copies of parent

Answer 19

daughter cells

Question 20

7. 3 Mitosis and the eukaryotic cell cycle

- What are the 3 interrelated systems to eukaryotic mitosis?

Answer 20

o 1. Master program = orderly + timely progression through cell cycle
o 2. Process of DNA synthesis replicates each DNA chromosome into near perfect copies
o 3. Structural + mechanical web of interwoven cables + motors of cytoskeleton separates daughter cells

Question 21

7. 3 a Chromosmes are genetic units divided by mitosis

- The hereditary information of eukaryote chromosomes is distributed where? What does this enable?

Answer 21

= distributed among DNA molecules

= o DNA combines with proteins for stability
o Assist in packaging during cell division + expression of genes

Question 22

7.3 a Chromosmes are genetic units divided by mitosis

Differnce between haploid, diploid, and ploidy?

Answer 22

Haploid:

• Haploid= n chromosomes not in pairs (singular)
  o Yeast can be both haploid and diploid
  Haploid organisms/cells have only one set of chromosomes, abbreviated as n.

Diploid:
- 2 copies of each chromosome 2n

Ploidy:
- # of chromosome sets = ploidy

Question 23

7. 3 a Chromosmes are genetic units divided by mitosis

- Waht occurs Before cell divides in mitosis?

Answer 23

replication of DNA provides in given chromosomes produces 2 identical copies of DNA = chromatids

Question 24

7. 3 a Chromosomes are genetic units divided by mitosis
   - Eukaryotes contain copies of each chromosome in where?

Are humans haploid of diploid?

Answer 24

nucleus

diploid

Question 25

7. 3 a Chromosmes are genetic units divided by mitosis | - What are chromatids?

Answer 25

= held together by proteins called cohesins

Question 26

7.3 a Chromosomes are genetic units divided by mitosis o During mitosis what happens to the sister chromatids? o Each daughter nucleus receives what from parent?

Answer 26

= separated = same genetic info as parent

Question 27

7.3 a Chromosomes are genetic units divided by mitosis | What is chromosome segregation?

Answer 27

 Equal division from cell division into daughter cells =

Question 28

7.3 a Chromosomes are genetic units divided by mitosis  Precision + replication + segregation in cell cycle creates what?  Mutations during replication create what?

Answer 28

= group of cells known as clones = cells of clone genetically similar but not identical

Question 29

7.3 a Chromosomes are genetic units divided by mitosis |  Single cell (zygote) is what?

Answer 29

parent cell

Question 30

7. 3 b Interface extends from one end of mitosis to the beginning of nest mitosis - Information of new daughter cell marks the beginning of what? - What is the first and longest stage

Answer 30

= (beginning of mitotic cell cycle) = interphase

Question 31

7.3 b Interface extends from one end of mitosis to the beginning of nest mitosis Interphase compromises of 3 phases of cell cycle, what are they?

Answer 31

 1 G1 phase • Cell carries out function and grows • Only phase of cell cycle that varies in length (others are uniform) • Pace of division depends on G1 • Stage where cell types stop dividing (shunt from G1 known as G0 phase)  2 S phase • DNA replication and chromosome duplication  G2 phase • Brief gap in cell cycle where cell growth continues, and cell prepares for mitosis and cytokinesis

Question 32

7. 3 b Interface extends from one end of mitosis to the beginning of nest mitosis - During all stages of interphase what happens to chromosomes?

Answer 32

= are organized and loosely packaged within nucleus

Question 33

7. 3 b Interface extends from one end of mitosis to the beginning of nest mitosis - Internal regularory controls what? o Internal controls are vulnerable to what?

Answer 33

= each phase of cell cycle (successful completion before next) also regulates # of cycles = cells, viruses, and signal molecules (hormone)

Question 34

7. 3 b Interface extends from one end of mitosis to the beginning of nest mitosis - In interphase the appropriate suite of genes are expressed for what? What happens to DNA during interphase?

Answer 34

= cell maintenance and metabolism = DNA is replicated

Question 35

7.3c After interphase, mitosis proceeds in 5 stages Mitosis involves what sort of events? What happens during these events?

Answer 35

= Mitosis involves nuclear + cytoplasmic events Nuclear: In nucleus: normal gene expression decreases, DNA condenses and kinetochores = built up Cytoplasmic: - In cytoplasm = cytoskeleton prepares for partitioning of chromosomes

Question 36

7. 3c After interphase, mitosis proceeds in 5 stages | 1. Prophase (before)?

Answer 36

a. Extended chromosomes replicated in interphase = condensed b. Condensation packs long DNA molecules for division in mitosis c. DNA compacted by winding double helix around small + charged protein to form nucleosome d. Proteins = histones make up nuclear core e. Short segment of DNA extends between one nucleosome and the next = linker f. Solenoid = coiled structure of nucleosomes g. During condensation = nucleus becomes smaller and disappears (shut down of RNA synthesis) h. In cytoplasm, miotic spindle forms between two centrosomes during their migration to poles i. Spindle = bundle of microtubules

Question 37

7. 3c After interphase, mitosis proceeds in 5 stages | 2. Prometaphase (in-between)

Answer 37

a. End of prophase, nuclear envelope breaks down b. Bundles of spindles of microtubules, grow from centrosomes @ opposing poles towards centre i. Attach @ Centro mirror of chromosomes c. Two sister chromatins held together by cohesin proteins d. Complex of proteins (kinetochore) has formed on each chromatid @ Centro mirror e. Microtubules bind to kinetochores = connection determine outcomes of mitosis b/c they attach sister chromatids of each chromosome to microtubules leading to opposite poles one big web i. Microtubules that don’t attach to chores, overall, those from opposite poles

Question 38

7. 3c After interphase, mitosis proceeds in 5 stages | 3. Metaphase

Answer 38

a. Spindle reaches final form; chromosomes move onto spindle alignment = metaphase plate b. Chromosomes complete condensation, X shape (based on location of centromirror and length and thickness of chromatin arms) c. When arms are assembled @ midpoint with two sister chromatids, metaphase leads to actual separation of chromatids d. Only chromosomes with Centro mirror towards mirror have X shape e. Chromosomes take on visible shape only when highly condensed f. Karyotype = fully arranged condensed chromosomes i. Very distinctive

Question 39

7. 3c After interphase, mitosis proceeds in 5 stages | 4. Anaphase (back) (segregation of whores to opposing poles brothel style)

Answer 39

a. Sister chromatids separate and move to opposing spindle poles b. Kinetochores move towards opposite poles = first sign of movement c. Movement continues until chromatids (known as daughter chromosomes) reach two poles = segregation

Question 40

7. 3c After interphase, mitosis proceeds in 5 stages | 5. Telophase (end) (pimp phase)

Answer 40

a. Spindle disassembles and chromosomes at each pole de-condense + return to extended state of interphase b. Condensation proceeds= reapportion of nucleolus c. RNA transcription resume + reformation of nuclear envelope around chromosomes @ each pole = two daughter nuclei d. Cytoskeleton resumes normal responsibilities (not managing whores) e. nuclear division is complete, cell has two nuclei - chromosomes = composed of pair of nucleic acid backbones making up DNA double helix - DNA molecules may attach to each other as sister chromatids - B/C sister chromatids remain attached to each other following DNA synthesis, referred to as one chromosome - Before replication, one chromosome is composed of one DNA double helix, after composed of two double helixes o DNA replication increases amount of DNA in nucleus but not number of chromosomes o During cell division, each of daughter cells receives one of sister chromatids

Question 41

7. 3 d cytokinesis completes cell division by dividing cell division of daughter cell - What is Cytokinesis? What does it follow? What does it produce? During what phases does it occur?

Answer 41

= division of cytoplasm = o Follows nuclear division stage of mitosis, produces two daughter cells containing one of daughter nuclei o Begins during telophase or anaphase

Question 42

7.3 d cytokinesis completes cell division by dividing cell division of daughter cell o Completion of cytokinesis means what? - Does this occur via same or different pathways?

Answer 42

= (2 new cells that have progressed to interphase) = o Proceeds by different pathways

Question 43

7.3 d cytokinesis completes cell division by dividing cell division of daughter cell Animals + Fungi vs Plants in cytoplasmic division? What determines cytoplasmic division?

Answer 43

 Animals and fungi: cytoplasm cut into two parts  Plants: new cell wall (cell plate) forms between daughter nuclei and grows until it divides cytoplasm = o Cytoplasmic division: determined by layer of microtubules @ formal spindle mid-point =  Furrowing: layer of microtubules @ formal spindle midpoint expands laterally until stretches between dividing cells

Question 44

7.3 d cytokinesis completes cell division by dividing cell division of daughter cell During furrowing, what does the developing layer consist of + what does this create? How is furrowing powered? Results in what?

Answer 44

= • Developing layer = band of microfilament inside plasma membrane develops = creates belt in between layers = • Powered by motor proteins = microfilament is constricted to help cell divide (belt tightens for division) • Constriction = groove in plasma membrane (furrow) resulting in separation of daughter cells

Question 45

7.3 d cytokinesis completes cell division by dividing cell division of daughter cell • What is cytoplasmic division? Function?

Answer 45

= isolation of daughter nuclei in daughter cells + distributes organelles and other structures equally between daughter cells

Question 46

7.3 d cytokinesis completes cell division by dividing cell division of daughter cell o What is Cell plate formation? • Vesicles contain components of what?

Answer 46

=  Plant cells are walled: plane of cell division = important  Plate cell formation, layer of microtubules @ spindle mid point = organixing site by vesicles produced by ER and golgi complex = cell wall

Question 47

7.3 d cytokinesis completes cell division by dividing cell division of daughter cell  the fusion of vesicle walls results in what forming?

Answer 47

= formation of cell plate (stretching across former spindle mid point)

Question 48

7.3 d cytokinesis completes cell division by dividing cell division of daughter cell Vesicle membrane fuses with what to create what?

Answer 48

fuses with plate to form cell wall

Question 49

7.4 Formation and Action of the mitotic spindle What is the Mitotic spindle central to? Made up of? What does mitotic activity depend on?

Answer 49

= central to mitosis and cytokinesis = Made up of microtubules and proteins =  Activity depends on changing patterns of organization during cell cycle

Question 50

7.4 Formation and Action of the mitotic spindle Microtubules are a major part of what phase? When mitosis approaches what do the microtubules do?

Answer 50

= interphase cytoskeleton of euk. Cells = Mitosis approaches = microtubules disassemble from interphase arrangements and reorganize into spindle (which grows until fills near entire cell)

Question 51

7.4 Formation and Action of the mitotic spindle • Reorganization of microtubules follows one of 2 paths. Describe.

Answer 51

follows one of 2 paths (depends on presence/absence of centrosome in interphase) o One organized spindle formation = same with or w/o presence of centrosome

Question 52

7.4 a Animals and Plants form spindles in different ways Do Animal and protists have chromosomes? What extends from this cite? Describe this site.

Answer 52

o Have centrosomes: site near nucleus where microtubules go outward in all directions  Main microtubule organizing centre of cell, anchoring microtubule cytoskeleton during interphase and positioning cytoplasmic organelles  Contains pair of centrioles • Important to mitotic spindle • Function: generate microtubules needed for flagella/cilia (aka cell motility)

Question 53

7.4 a Animals and Plants form spindles in different ways * DNA replication in S phase? * Prophase in M phase? * Late prophase:

Answer 53

= centrioles in chromosome duplicate producing 2 pairs of centrioles = : centrosomes separate into 2 parts o Duplicated chromosomes (with centrioles inside continue to separate until they reach opposite poles) o Movement of centrosomes = microtubules between lengthen and increase = centrosomes = fully separated, o microtubules extend between = large mass – early spindle o when nucelar envelope breaks down @ end of prophase = spindle moves into region once occupied by nucleus and grows until it fits cytoplasm o microtubules grow in length o Asters = centrosomes at the spindle tip (from pole ends)  Separation = spindles ensure daughter cells receive pair of chromosomes • No centrioles or centrosome present in flowering plants

Question 54

7.4 a Animals and Plants form spindles in different way Asters?

Answer 54

= centrosomes at the spindle tip (from pole ends)

Question 55

7.4 b Mitotic Spindles can move chromosomes by a combination of two mechanisms - Fully formed spindles @ metaphase = contain what? o 1. Kinetochore microtubules?  Chromosome move toward poles via what? o 2. non-kinetochore microtubules? The Separation of chromosomes @ anaphase are a combo of what 2 groups?

Answer 55

= many microtubules (2 groups) =  Connect chromosomes to spindle poles  Chromosomes climb to poles via microtubules using motor proteins in kinetochores  Tubulin subunits of kinetochore microtubules disassemble when kinetochore climbs (microtubules shorten as a result)  Kinetochore microtubules do not move with respect to poles during anaphase = motor proteins @ spindle poles pull kinetochore microtubules poleward (disassembly of microtubules into tubulin) =  Extend between spindle poles w/o connecting to chromosomes (form microtubule overlap)  Elongation of spindles = cell elongation in metaphase and anaphase  Pushing movement = produced by microtubules sliding over one another (overlap) powered by microtubule motors (ex of dynein movement) = kineto and non-kinetochores

Question 56

7. 5 b Cell-Cycle checkpoints ensure accurate cell division - Cell has control points aka what? - 3 key checkpoints What do they do? Describe each?

Answer 56

= control proteins = cyclins = (prevent next phase from occurring until current phase is carried out effectively) 1. G/S1 Checkpoint: a. Main point in cell cycle b. Cell cycle arrest = cell stops proceeding through cell cycle if DNA is damaged c. Primary checkpoint for extracellular reading for cell growth and division (hormone or growth factor absent = potential arrest) 2. G2/M checkpoint a. Junction b/w G2 and M phases b. Arrests occur if = DNA not replicated fully in S, DNA is damaged 3. Mitotic spindle checkpoint a. Within M phase before metaphase b. Assesses whether chromosomes are attached properly to mitotic spindle for proper metaphase plate alignment c. Essential for production of daughter cells d. One cell begins anaphase = irreversibly committed to completing M

Question 57

7. 5 c Cyclins and cyclin-dependant kinases are the internal controls that directly regulate cell division - Regulation of cell = internal control system of protein cyclins and enzymes called  Activity of CDK =  Concentration of cyclins change in cell cycle (b/c of what?  Regulation of cyclin-CDK complexes activity are coupled with what ?

Answer 57

= cyclin-dependant kinases o CDK = protein kinase that phosphorylates + regulates activity of target proteins = DNA replication, mitosis, cytokinesis  Cyclin dependant b/c their activity depends on if they are bound to cyclin molecule = synthesis and degradation), concentration of CDK = constant = cell-cycle checkpoints

Question 58

7. 5 d External controls coordinate the mitotic cell cycle of individual cells with the overall activities of the organism - Internal controls regulating cell-cycle = respond to what? o Animals signal molecules? o Plant signal molecules? - External factors bind to what? what does this trigger? o Effects what? o Cell surface receptors in animals = recognize contact with molecules of extracellular matrix – results in what?

Answer 58

= signal molecules (from outside of dividing cell) = peptide hormones, and growth or death factors = growth hormones = bind to receptors on cell surface, response = triggering of reactions inside of cell (often include adding phosphate to cyclin-CDK complexes – affects function) = speed, slow, stop progress of cell division = in inhibit division of cell (contact inhibition)

Question 59

7. 5 e Stem cells exhibit asymmetric cell division | - What is Asymmetric cell division

Answer 59

= producing twin daughter cells

Question 60

7.5 f Most cells in multicellular body cannot divide indefinitely - what is Cellular senescence? - What are the 2 contributing factors?

Answer 60

= loss of constant division ability over time = 1. DNA damage 2. Telomere shortening a. Telomere: repetitive DNA sequences added to end of chromosomes b. Once telomere diminish to minimum length = cell division stops

Question 61

7. 5 g Cell-cycle controls are lost in cancer | - What are Cancer cells? What do they do to the CDK cyclin-system?

Answer 61

= mutations in variety of genes, many encode cyclin-CDK system- when mutated = oncogenes o System breaks down = no more checkpoints, unlimited division

Question 62

7.5h Some cells are programmed to die - What is Apoptosis o Initiation of cell death results from what? o Can healthy cells undergo apoptosis? Why?

Answer 62

= programmed cell death o Ancient mechanism common in mult. Euk. = internal or external signals = for specific functions (fingers result of web skin cell apoptosis)

Question 63

8.1 Mechanism of Genetic Recombination - Genetic variability in population allows populations to what? o What is the source of variability in populations?: o Diversity is amplified by what? What is this process called?

Answer 63

= evolve = mutation in DNA sequence = = amplified via shuffling of existing mutations in different combos: Genetic recombination  Genetic recombination = origin of sexual aspect  Without genetic recombination = asexual reproduction (clones)

Question 64

8. 1 Mechanism of Genetic Recombination - Recombination requires what? What is DNA? DNA Recombination occurs between what regions? What does Homology allow?

Answer 64

= o 2 DNA double helix o Mechanism for bringing DNA into proximity + collection of enzymes for “cut, exchange, paste” DNA = - DNA: o Double helix o Sugar phosphate backbones (winds)  Held together by strong covalent bonds o Paired bases (ribs)  Pairs with partners via weak hydrogen bonds • H bonds can be broken = separates DNA molecule = forms template for cell division replication = regions of similar DNA base sequences o Regions = homologous = allows diff. DNA molecules to position and combine o Homologous regions of DNA: o Paired with enzymes that separate H bonds of one double helix + allows reassociation of bases with complimentary bases homologous (non-sister) chromatid  Involves cutting sugar-phosphate group and linking to non-sister chromatids

Question 65

8.1 Mechanism of Genetic Recombination | What is one recombination event?

Answer 65

Cutting and pasting 4 DNA backbones

Question 66

What is Sexual Reproduction? What is an Evolutionary advantage to sexual reproduction?

Answer 66

= Produces offspring by male/female union (gametes) o Meiosis produces gametes with half chromosome number = : genetic shuffling of sex = unique offspring