Chapter 10: Cell Reproduction: Cell Cycle and Reproduction

DNA is decondensed during replication because

genes must be in this form for transcription

condensed DNA ensures that

daughter cells receive the same genetic material during cell division

karyotype

an individual’s complete set of chromosomes

humans have (1) chromosomes that are (2)

46, 99% identical

homologous chromosomes (autosomes) consist of

22 pairs of chromosomes (44 single chromosomes in total)

sex chromosomes

2 non-pairs of chromosomes

after DNA replication, each chromosomes has 2 copies of identical (1)

sister chromatids

sister chromatids are joined at the

centromere

interphase consists of

normal cell growth, DNA replication, and preparation for the M phase

during the first stage of interphase, G1 phase (gap 1),

the cell is born and grows, and makes protein, mRNA and DNA

during the second stage of interphase, S phase (DNA synthesis/replication),

DNA replicates from 1 chromosome → 2 chromosomes, and centrosomes duplicate

during the third stage of interphase, G2 phase (gap 2),

the cell prepares to divide for mitosis, and organelles duplicate

the purpose of the mitotic phase is to produce

2 identical daughter cells

during mitosis (karyokinesis),

the nucleus and its contents divide evenly into 2 daughter nuclei

during the first step of mitosis, prophase,

nuclear envelop starts to break down, organelles move towards cell edges, nucleolus disappears, centrosomes (microtubules) begin moving to poles, microtubules of mitotic spindle forms, and chromosomes start condensing

during the second step of mitosis, prometaphase,

nuclear membrane breaks completely, and kinetochore (protein structure) develops in each sister chromatid’s centromeric region

during the prometaphase stage of mitosis, kinetochore (protein structure) develops to

attract and bind microtubules of mitotic spindle

during the third step of mitosis, metaphase,

chromosomes line up at the metaphase plate (cell equator/center), and cohesion proteins keep sister chromatids attached

during the metaphase stage of mitosis, cohesion proteins develops to

keep sister chromatids attached

during the fourth step of mitosis, anaphase,

cohesion degrades so chromatids separate and move in opposite directions towards their microtubules-attached centrosomes

during the fifth step of mitosis, telophase,

chromosomes decondense at opposite poles, spindles depolymerize into tubular monomers, nuclear envelopes form around chromosomes, and nucleosomes appear within the nuclear area

cytokinesis overlaps with

mitosis and involves the cytoplasms and organelles dividing into 2

eukaryotes and proakryotes under go different processes of

cytoplasmic content division

animal cell cytokinesis involves

microfilaments helping to separate cells into 2 via the cleavage furrow

in animal cell cytokinesis, the cleavage furrow is

a contracting ring of microfilaments

during plant cell cytokinesis

vesicles help create a cell wall until enough material is brought for the cell wall

the G0 phase (resting phase) is when

the cell exits the cell cycle if nutrients is scarce or if cells will never divide again (e.g., adult cells, neurons)

cell progression regulation can be affected by external factors such as

presence of growth hormone (GH), nutrient availability, and crowding

cell progression regulation can be affected is by internal factors such as

DNA damage

the G1 checkpoint during cell progression checks for

external conditions, nutrients reserves, and DNA damage

the G2 checkpoint during cell progression assesses for

cell size, protein reserves, and DNA replication and damage

the metaphase checkpoint during cell progression determines

whether all sister chromatids are correctly attached to the spindle microtubules

during the metaphase checkpoint, mitosis halts until all kinetochores are

anchored to spindles from opposite cell ends

positive regulators are cell cycle regulators that

promote movement to next step of the cell cycle

cyclins, a family of proteins, are a type of positive regulators that

act as part of a complex by interacting and activating CDK (cyclin dependent kinase)

cyclin and CDK phosphorylates

target protein that pushes cell cycle forward

negative regulators are cell cycle regulators that

stop advancement of the cell cycle

cancer is a

cell cycle disease in which cells dont listen to regulators, so they continue cell division.

cancer is harmful because

cells only divide when they need to

tumors are

cell masses made of cancer cells

benign tumors are

restricted to one tissue

malignant tumors

spread to other tissue via lymph vessels or blood vessels (metastasis)

proto-oncogens are normal genes that

code for the positive cell cycle regulators

oncogenes are mutated

proto-oncogens that cause a cell to become cancerous

tumor suppressors are

negative cell cycle regulators that stop cells from dividing without regulation