Chapter 10 Cell Reproduction

cell cycle

represents the continuity of life based upon the reproduction of cells

cell division

how do unicellular organisms reproduce?

development from a fertilized cell, growth, and repair

multicellular organisms depend on cell division for:

cell division

integral part of the cell cycle but not the only part

results in genetically identical daughter cells by duplicating genetic material

genome

a cell’s endowment of DNA/a cells genetic information

chromosomes

a high concentration of DNA molecules in a cell

chromatin

a complex of DNA and protein that condenses during cell division

contains histones

somatic cells

body cells that have two sets of chromosomes (ex: liver cells, skin cells, kidney cells)

gametes

sex cells with one set of chromosomes

cell division preparation

DNA is replicated and the chromosomes condense into sister chromatids

centromere

a structure that connects the two sister chromatids together (NOT ALWAYS in the center)

mitosis

the division of the nucleus

cytokinesis

division of the cytoplasm

meiosis

sex cells that are produced after a reduction in chromosome number

mitotic phase

the phase made up of mitosis and cytokinesis

alternates with interphase in the cell cycle

interphase phases

1) G1

2) S

3) G2

prophase, prometaphase, metaphase, anaphase, telophase

5 phases of mitosis

G2 of interphase

chromosomes are found in a nucleolus and replicated but decondensed

prophase

asters start to form from the centrosomes and slowly move to opposing poles in the cell

nucleolus disappears

nuclear envelop slowly dissolves

chromosomes condense

prometaphase

chromosomes are attached to kinetochore microtubules but not quite at the center of the cell

kinetochore microtubules

strands that attach to the kinetochore and centrosome — connect spindles to chromosomes

metaphase

chromosomes are lined up in the middle of the cell on the metaphase plate

anaphase

mitosis phase where daughter chromosomes move closer to their nearest aster

telophase and cytokinesis

a cleavage furrow appears between the two cells

a nucleolus and nuclear envelope forms for each set of cells’ genetic information

cells pinch off into new cells

mitotic spindle

apparatus of microtubules that controls chromosome movement during mitosis

arise from the centrosome and includes spindle microtubules and asters

tubulins

what are microtubules made of

microtubules (tubulin polymers)

hollow tubes made of proteins where the wall consists of 13 columns of tubulin molecules

centrosome

found in animal cells and assist with chromosome movement

two

how many sister chromatids does each duplicated chromosome contain

motor protein

protein powered by ATP that climbs up the microtubule to pull the sister chromatid towards the aster and breaks down the microtubule to be recycled later

motor protein method

what is the more common method of sister chromatid separation

cleavage

forming a cleavage furrow during cytokinesis

cell plate

structure that forms during cytokinesis in plant cells

prokaryotes (bacteris)

what kind of organisms don’t go through mitosis

binary fission

how do prokaryote (bacteria) reproduce

binary fission process

circular bacterial chromosome replicates and two daughter chromosomes actively move apart

septum forms and divides the cell

certain protists, diatoms, and yeasts

organisms that exhibit types of cell division that seem intermediate between binary fission and mitosis

help to support the idea that mitosis likely evolved from bacterial cell division

molecular control system

how is the cell cycle regulated

cell cycle control system

regulates progress through cell cycle

G0 phase

non-dividing phase of the cell

G1 checkpoint

checkpoint before the S phase that determines whether a cell can undergo the cell cycle

cyclins

regulatory protein that fluctuates in concentration during the cell cycle

cyclin dependent kinases (Cdks)

-kinase that activates with a certain amount of cyclin and triggers cell division

-regulatory enzyme that completes phosphorylation

phosphorylation

addition of a phosphate group process

middle of M phase

part of cell cycle where Cdk and Mitosis Promoting Factor (MPF) activity spike

metaphase

when does cyclin and kinase activity peak?

late S phase through G2

when is cyclin synthesized in the cell cycle

M checkpoint purpose

ensure all sister chromatids are attached to spindles at the kinetochore so no genetic material is left behind

G2 checkpoint purpose

checks DNA replication and whether cell is ready to duplicate

G1, S, G2, M

chronological order of cell cycle

density dependent inhibition

crowded cells stop dividing out of lack of space

anchorage dependence

cells must be attached to a (non-cellular surface) substratum to divide

cancer cells

-mutated cells that exhibit neither density dependent inhibition nor anchorage dependence (some will float around in medium)

-do not respond normally to the body’s control mechanisms

-form tumors

causes of cancer

increased cell division

decreased cell death

apoptosis

programmed cell death

genes associated with cancer

genes that normally regulate cell growth and cell cycle (ie: genes for growth factors and their receptors and signaling pathways)

oncogenes

abnormal cancer causing versions of proto-oncogenes

proto-oncogenes

normal cellular genes that code for proteins that control normal cell growth and division

ways proto-oncogene can change to oncogene

1) point mutation within a control element

2) point mutation within the gene

Ras

signaling protein that when active, turns on cell cycle proteins and responds indirectly to the presence of growth factors

tumor suppressor genes

encode proteins that inhibit abnormal cell division

p53 gene

gene that encodes a tumor-suppressor protein that is a specific transcription factor that promotes the synthesis of the cell cycle-inhibiting proteins

responds to DNA damage and suppresses cell cycle if DNA damage is detected

how normal cells are converted to cancer cells

accumulation of multiple mutations affecting proto-oncogenes and tumor suppressor genes

metastasize

exporting cancer cells to other parts of the body where they may form secondary tumors

how viruses promote cancer growth

integration of viral DNA into the cell’s genome

cause genetic changes to host gene

virus carries oncogene

FtsZ

protein the determines where the septum will form in prokaryotic cell division