Final Exam Chapt 9

What is a cell cycle?

ordered sequence of events by which a cell grows, replicates its DNA, and divides into two daughter cells

What is cell division?

the physical process that produces these new cells.

What are the functions of cell division?

Multicellular organisms use cell division for
growth, maintenance and repair of cells and
tissues.

What are the functions of cell division?

Single-celled organisms use cell division to
reproduce.

What is a genome?

a cell’s DNA, packaged as a double-stranded DNA molecule

What are somatic cells?

Are diploid body cells responsible for growth and repair

What are Gametes

are haploid reproductive cells that carry genetic material to offspring. sex cells

What is the difference between somatic cells and gametes?

Somatic cells are diploid body cells 46 chromosomes & Gametes are haploid reproductive cells 23 chromosomes

Describe how DNA is packaged

DNA is tightly packed in the nucleus by wrapping around histone proteins to form nucleosomes, which then fold into chromatin fibers, allowing meters of DNA to fit into a tiny cell nucleus.

What are the two phases of the cell cycle?

Interphase (blue) is the time for normal growth and preparation for cell division

What are the two phases of the cell cycle?

Mitotic phase (red), in which the replicated DNA and cytoplasm are split and the cell divides

3 Phases of Interphase #1

G1 Phase (first gap): cell growth & metabolic activityn(protein synthesis)

3 Phases of Interphase #2

S Phase: is when DNA synthesis occurs, Identical copies of the DNA molecules (sister chromatids) are joined at the centromere
• Centrosomes produce the mitotic
spindles to move the chromosome

3 Phases of Interphase #3

G2 Phase (second gap) Energy is replenished, organelles reproduce and cytoskeleton breaks down

What are the stages of mitosis and what happens in each?

Karyokinesis, also called “mitosis” or nuclear division, is the first step

What are the stages of mitosis and what happens in each?

Prophase: Sister chromatids condense, Nuclear envelope breaks down, Spindle fibers appear

What are the stages of mitosis and what happens in each?

Prometaphase (late prophase): Sister chromatids develop a protein kinetochore in the centromere region which attaches the chromatids to the spindle microtubules

What are the stages of mitosis and what happens in each?

Metaphase: • Chromosomes line up along metaphase plate
(“equatorial plate”)
• Sister chromatids remain attached by cohesion
proteins line up in the middle
• Centrosomes are at opposite poles
• Chromosomes are maximally condensed

What are the stages of mitosis and what happens in each?

Anaphase: • Sister chromatids are pulled apart by spindle
fibers and separated they split in half
• Each chromatid is now called a chromosome
• The cell elongates

What are the stages of mitosis and what happens in each?

Telophase: • Chromosomes reach opposite poles and begin to
decondense (unravel)
• Spindle fibers break down
• Nuclear envelope reassembles around the chromosomes
• Cytokinesis is visible in animal cells

What are the stages of mitosis and what happens in each?

Cytokinesis: • Cell division is completed the physical separation of the cytoplasmic components into two daughter cells. cells finally completely split

What are the end products of mitosis?

two genetically identical daughter cells, each with the same number of chromosomes as the original parent cell. Cytokinesis

What happens during cytokinesis?

A single cell physically divides its cytoplasm to form two distinct daughter cells, completing cell division.

How does cytokinesis differ between plants and animals?

Cytokinesis in plant cells new wall being formed from vesicles containing carbs and structural protein cell wall sepereates cells. while Animal cells have Contractile ring- band of proteins in animal cells, begins to pinch in (cleavage furrow) and split cells into 2

What is a checkpoint? What happens at each checkpoint discussed in lecture?

In the cell cycle is a regulatory point where the cell evaluates internal and external conditions to decide whether to proceed to the next phase of division or pause for repairs G1 check point decides if it’s a good idea to divide checks for damage allat. G2 check point copies chromosomes make sure has enough energy. During metaphase checkpoint makes sure chromosomes are lined up and spindle fibers are attached.

Positive Regulators

push cell cycle forward. Examples: cylins & Cyclin-Dependent Kinases (Cdks)

Negative Regulators

stop advancement of the cell cycle. Examples: Retinoblastoma Protein (Rb) & p53, and p21

What are Proto-oncogenes & relationship with cancer

Normal genes that code for positive cell cycle regulators. can lead to excessive cell proliferation. when checkpoints fail their jobs.

What are Tumor suppressor genes & relationship with cancer

Normal genes that code for negative regulator proteins. when tumor suppressor genes are inactivated, the control over cell growth is lost. when checkpoints fail their jobs.

What is binary fission?

asexual reproduction process in which a single cell divides into two genetically identical daughter cells.

What is asexual reproduction?

involves a single parent producing genetically identical offspring.

What is sexual reproduction?

requires two parents and results in genetically unique offspring.

What is a diploid cell?

Contain two complete sets of chromosomes (2n), one from each parent.

What is a haploid cell?

Have only one complete set of chromosomes (n),

What are homologous chromosomes?

pairs of chromosomes in a diploid organism that have the same structure and carry the same genes, one inherited from each parent.

Explain crossing over and the associated structures (chiasmata, tetrads)

Crossing over is the exchange of genetic material between non-sister chromatids of homologous chromosomes during prophase I of meiosis. A tetrad is a group of four chromatids 2 pairs from homologous chromosomes. A chiasma is the physical point of contact between two non-sister chromatids after crossing over has occurred

meiosis

diploid to haploid 46 to 23

point of meiosis

sexual reproduction (gametes)

meiosis Prophase1

homologous pair will synapse come together by crossing over mom and dad chromosome join together red and blue mix

Meiosis Metaphase 1

lined up in middle as pairs

Meiosis Anaphase 1

separated on opposite sides as pairs.

Meiosis Telophase 1

pairs get split into half amount of number, Haploid.