Chapter 9 Cell Cycle Flashcards
In unicellular organisms division of one cell..
Reproduces the entire organism
Cell Cycle
The life of a cell from its formation to its own division
Genome
All the DNA in a cell
DNA molecules in a cell are packaged into
Chromosomes
Chromatin
A complex of DNA and protein in Eukaryotic chromosomes
Somatic cells have _____ sets of chromosomes
2
Gametes are reproductive cells and have one set of
Chromosomes
Sister Chromatids
Joined identical copies of the original chromosome
The ________ is where the two chromatids are most closely attached
Centromere
Eukaryotic cell division consist of __________, the division of the genetic material in the nucleus.
____________ is the division of the cytoplasm
Mitosis, Cytokinesis
Gametes are produced by
Meiosis
Meiosis yields non identical daughter cells that have only _______ set of chromosomes
1
___________developed dyes to observe chromosomes during mitosis and cytokinesis in 1882
Walther Flemming
The cell cycle consists of
Mototic phase and Interphase
Interphase can be divided into 3 subphases
G1 Phase
S Phase
G2 Phase
The cell grows during all three phases but chromosomes are duplicated only during the S phase
Mitosis is divided into 5 phases
Prophase Prometaphase Metaphase Anaphase Telophase
Mitotic Spindle
A structure made of microtubules and associates proteins
Mitotic Spindle controls
Chromosome movement during mitosis
In animal cells assembly of spindle microtubules begins in the _________, a type of microtubule organizing center
Centrosome
The centrosome replicates during________
Interphase
The two centrosomes migrate to opposite ends of the cell during
Prophase and prometaphase
Aster
Radical array of short microtubules that extends from each centrosome
The spindle includes the
Centrosomes, the spindle microtubules and the asters
Kinetochores
Are protein complexes that assemble on sections of DNA at centromeres
During __________ , some spindle microtubules attach to the kinetochors of chromosomes and begin to move the chromosomes
Prometaphase
At metaphase the centeomeres of all the chromosomes are at the ___________, an imaginary structure at the midway point between the spindles two poles
Metaphase plate
Sister chromatids separate and move along the kinetochore microtubules towards opposite ends of the cell during_________
Anaphase
The microtubules shorten by
Depolymerizing at their kinetochore ends
Chromosomes are also reeled in by
Motor proteins at spindle poles, and microtubules depolymerize after they pass by the motor proteins
___________ from opposite poles overlap and push against each other elongating the cell
Nonkinetochore microtubules
In this phase, duplicate groups of chromosomes have arrived at opposite ends of the elongated parent cell
Anaphase
Cytokinesis begins during ________or __________ , and the spindle eventually disassembles
Anaphase or telophase
Cytokinesis occurs by a process known as
Cleavage, forming a cleavage furrow
In plant cells a _________forms during cytokinesis
Cell plate
Prokaryotes reproduce by a type of cell division called
Binary fission
In ecoli single chromosome replicates at the
Origin of replication
Mitosis likely evolved from
Binary fission
The cell cycle is driven by specific signaling molecules present in the
Cytoplasm
The __________controls the sequential events of the cell cycle
Cell cycle control system
The cell cycle control system is regulated by both
Internal and external controls
The clock has specific ___________ where the cell cycle stops until a go ahead signal is received
Checkpoints
For many cells, the ___checkpoint seems to be the most important.
G1, if a cell receives a go ahead signal at the G1 it will usually complete S, G2 and M phases
If a cell does not receive the go ahead signal, it will exit the cycle switching into a non dividing state called
Go Phase
The cell cycle is regulated by a set of __________ and __________including kinases and proteins called_________
Regulatory proteins, protein complexes, cyclins
Some external signals are __________, Proteins released by certain cells that stimulate other cells to divide
Growth factors
An example of external signals is _____________ I which crowded cells stop dividing
Dependent inhibition
Anchorage Dependence
Signal in which cells must be attached to a substratum in order to divide
________ cells exhibit neither density dependent inhibition nor anchorage dependence
Cancer
A normal cell is converted to a cancer cell by a process called
Transformation
If abnormal cells remain only at the original site the lump is called a
Benign tumor
DNA replication produces two identical DNA molecules called ________, which separate during mitosis
Sister chromatids
Microtubules attach to chromosomes at the
Kinetochore
Mitotic spindle
A cell structure consisting of microtubules which forms during early mitosis
During interphase, most of the nucleus is filled with a complex of DNA and protein in a dispersed form called
Chromatin
The ____________are the organizing centers for microtubules involved in separating chromosomes during mitosis
Centrosomes
The DNA is replicated in the
S phase
The centrosome replicates in the
G2 phase
G1
Cells create organelles for energy and protein production and increase in size
S Stage
Cell replicates it’s genetic material
G2
After synthesis but before Prophase
Prophase
Condensation of chromatin into chromosomes
Centriole pairs separate and move towards opposite poles of the cell
Centrioles form spindle fibers
Metaphase
Chromosomes convene on the metaphase plate
Anaphase
Begins when paired centromeres of each chromosome separate
The kinetochore fibers shorten and the nonkinetochore fibers lengthen
Each chromatid is now considered a chromosome
Telephase
Reverse of prophase
Spindle apparatus disappears
Nuclear membrane reforms around each set of chromosomes and the nucleoli reappear
Cytokinesis
Formation of a cleavage furrow in animal cells which punches the cell in two
