Chapter 12 The Cell Cycle Flashcards
_____ chromosomes for haploid and ______ chromosomes for diploid
23, 46
DNA plus the proteins makes up….
Chromosomes
All the DNA together in one cell refers to the ….
Genome
DNA molecules are packaged into thread like packages
DNA plus the proteins
Chromosomes
Chromosomes are made up of ___________
Chromatin
Compacted DNA?
When the cells get ready to divide, the chromosomes _________ enough time be seen with a light microscope
Compact
Somatic cells have _____ sets of chromosomes
Gametes cells have _______ as many chromosomes as somatic cells
2, half
Reveals number, size, and from of chromosomes in an actively dividing cell
Karyotype, genetic analysis
22 pairs in humans is called
Autosomes
_____ pair of sex chromosomes in humans
XX or XY
1
2n represents….
n represents…..
Diploid
Haploid
Sex chromosomes are not homologous. True or false?
True
In diploid species m, members of a pair of chromosomes are called ————-
Homologous
Each homologue nearly identical in size and genetic composition
Sex chromosomes are very __________ from each other.
Do X and Y differ in their size and composition?
Different, yes
In preparation for cell division, DNA is ____________ and the chromosomes are _______
Replicated, condensed
What are the joined copies of the original chromosome called?
Sister chromatids
- The narrow “waist” of the duplicated chromosomes
- two chromatids are most closely attached
Centromere
Chromosomes are identified by…..
Size, location of centromere, and banding pattern
The short arm on chromosomes is ____, long arm is _____
Which one is on top?
p, q
Short arm
When the centromere is in the middle….
Metacentric
When the location of the centromere is off center
Submetacentric
When the location of the centromere is near the end….
Acrocentric
When the centromere location is at the end….
Telocentric
Giemsa stain gives _____ banding
G
In mitosis cell division results in daughter cells with _________ genetic information
Identical
Cell division in meiosis results in ____________ daughter cells
Non identical
During cell division the two sister chromatids is each duplicated chromosomes spectate and move into two nuclei
Once separate, the chromatids are called…
Chromosomes
The cell cycle consists of what two phases?
Interphase-(cell growth and copying of chromosomes in preparation for cell division) this is the longest phase
Mitotic (M) phase- (mitosis and cytokines)
dividing phase
Which phase accounts for 90% of the cell cycle?
Interphase
Interphase is divided into what three subphases?
Cell grows during all three phases*
G1 phase- “first gap” makes proteins
S phase- “synthesis” sister chromatids are made
G2 phase- “second gap” makes proteins for cell division
S phase
- DNA is replicated
- sister chromatids- two identical copies with associated proteins
- centromere
- kinetochore
What are the two phases of M phase?
Mitosis and cytokinesis
What happens in the mitosis phase of the M phase?
Divide one cell into two
What happens in the cytokinesis phase of the M phase?
Division of the cytoplasm, follows in most cases
- 2 new cells genetically identical to the original
- mother cells
- daughter cells
- mitosis and cytokinesis
- can be for asexual reproduction or for production and maintenance of multicellularity
M phase mitotic cell division
Mitosis is divided into what five phases?
Prophase Prometaphase Metaphase Anaphase Telophase
______________ overlaps the latter stages of mitosis
Cytokinesis
What is responsible for organizing and sorting the chromosomes during mitosis
Mitotic spindles
What are mitotic spindles composed of?
Microtubules
What is responsible for the sorting process that ensures that each daughter cell will obtain the correct number and type of chromosomes
Mitotic spindles
Animal cells have centrioles that are not found in many other eukaryotes. True or false
True
Microtubule organizing center (MTOCs) are derives from ……
Centrosomes
A single centrosome duplicated a the beginning of…..
Each defines a pole
M phase
Spindle is formed from _________
Tubulin proteins
Microtubules
What are the three types of microtubules?
- astral -position spindle in cell
- polar -separate two poles
- kinetochore -attached to kinetochore bound to centromeres of each chromosome
What happens in prophase?
- chromosomes have already replicated to produce 12 chromatids, joined as six pairs of sister chromatids
- neclear membrane dissociates into small vesicles
- chromatids condense into highly compacted structures that are readily visible by light microscopy
- the nucleoli disappear
- mitotic spindle begins to form
What happens in prometaphase?
- nuclear envelope completely fragments
- mitotic spindle is fully formed during this phase
- centrosomes move apart and demarcate the two poles
- Spindle fibers interact with sister chromatids
- two kinetochore microtubles form opposite poles
- nonkinetichore microtubules interact with those from opposite pole of the spindle
What happens in metaphase?
- centrosomes at opposite poles of the cell
- pairs of sister chromatids are aligned along a plane halfway between the poles called metaphase plate
- organized into a single row
- when alignment is complete, the cell is in metaphase
What happens in anaphase?
- Connection between the pairs of sister chromatids are broken (-separate cleaves cohesions (proteins) holding together sister chromatids
- each chromatid, now an individual chromosome, is linked to only of the two poles by one or more kinetochore microtubules
- kinetochore microtubules shorten, pulling the chromosomes toward the pole to which they are attached
- two poles move farther away from each other as overlapping polar microtubules lengthen and push against each other
What happens in telophase?
- chromosomes have reached their respective poles and decondense
- nuclear membranes now re-form to produce two separate nuclei
- nucleoli reappear
- spindle microtubules depolymerize
What is a structure made of microtubules that controls chromosome movement during mitosis?
Mitotic spindle
In animal cells, assembly of spindle microtubules begins in the ______________, the microtubule organizing center
Centrosomes
The centrosomes replicates during __________,forming two centrosomes that migrate to opposite ends of the cell during _________ and ___________
Interphase,
Prophase and Prometaphase
An __________ (a radial array of short microtubules) extends from each centrosome
Aster
The spindle includes…..
The centrosome, the spindle microtubules, and the asters
During _____________, some spindle microtubules attach to the kinetochores of chromosomes and begin to move the chromosomes
Prometaphase
Protein complexes associated with centromeres?
Kinetochores
At metaphase, the chromosomes are all lined up at the____________, an imaginary structure at the midway point between the spindle’s two poles
Metaphase plate
What phase do sister chromatids separate and move along the kinetochore microtubules toward opposite ends of the cell?
Anaphase
The microtubules shorten by _____________ at their kinetochore ends
Deploymerizing
______________ microtubules from opposite poles overlap and push against each other, elongating the cell
Nonkinetochore
In what phase do genetically identical daughter nuclei form at opposite ends of the cell?
Telophase
Cytokinesis begins during ___________ or _____________ and the spindle eventually disassembles
Anaphase or telophase
In animal cells, cytokinesis occurs by a process known as ____________, forming a ______________
Cleavage, cleavage furrow
In plant cells, a _________ forms during cytokinesis
Cell plate
Binary fission in bacteria?
The chromosome replicates (beginning at the origin of replication*)
- to daughter chromosomes actively move apart
- plasma membrane pinches inward
How are eukaryotic cells are regulated by specific chemical signals in the ___________
Cytoplasm
The cell cycle Control system is regulated by both __________ and ___________ controls
External
- environmental conditions
- signaling molecules
Internal
- cell cycle control molecules
- checkpoints
Checkpoint that stops if DNA is damaged ***
G1
Checkpoint that checks to make sure copies were made, also if DNA was damaged, and if proteins are present ***
G2
Checkpoint that checks if sister chromatids are lined up on the metaphase plate
M checkpoint
Three critical regulatory points or checkpoints in eukaryotes
- G1 checkpoint (restriction point)
- G2 checkpoint
- metaphase checkpoint
For many cells the _______ checkpoint seems to be the most important
G1
If cells do not receive the go ahead signal, it will exit the cycle, switching into a non-dividing state called the…
G0 phase
Two types of regulatory proteins that are involved in the cell cycle control:
Cyclins- (cyclically fluctuating concentrations in cells)
Cyclin-dependent kinases (Cdks)- actively fuctuates because it is controlled by cyclins
Is cyclin active by itself?
No
Kinases controlling cell cycle must bind to a ________ to be active
Cyclin
Cyclin + Cdk =
MFP (maturation-promoting factor)
Cyclin-Cdk complex that triggers a cell’s passage past the G2 checkpoint into the M phase
MPF (maturation-promoting factor)
MPF peaks during?
Metaphase
Internal vs. external signals at checkpoints
Internal- kinetochores not attached to spindle microtubules send a molecular signal that delays anaphase
External- growth factor (required for cell division) -proteins released by certain cells that stimulate other cells to divide, playlet-derived growth factor
When crowded cells stop dividing this is called…
Density-dependent inhibition
When cells must be attached to divide, most animal cells
Anchorage dependence
A normal cell is converted to a cancerous cell by a process called ______________
Transformation
