Biology Chapter 12 The Cell Cycle

Orderly set of stages from the first division of a eukaryotic cell to the time the resulting daughter cells divide.

This describes what?

Major 2 Stages of the Cell Cycle

- Cell cycle main checkpoint

- If DNA is damaged, apoptosis will occur

- Otherwise, cell is committed to divide when growth signals are present and nutrients are available

- Growth and DNA replication phase

-Precise and accurate DNA replication is necessary to prevent genetic abnormalities which often lead to cell death or disease

- Duplicates a microtubule-organizing structure called the centrosome

- Mitosis checkpoint. Mitosis will occur if DNA has replicated properly. Apoptosis will occur if DNA is damaged and cannot be repaired

- Spindle assembly checkpoint. Mitosis will not continue if chromosomes are not properly aligned.

Stages of Mitosis (5)

- Most of the cell cycle is spent in this phase 90%

- Cell performs its usual functions

- Time spent in this phase varies by cell type

- Nerve and muscle cells do not complete the cell cycle (remain in G0 stage)

- G1, S and G2 phases

- Cell is in recovery from previous decision

- Cell doubles its organelles

- Cell grows in size

- Cell accumulates raw materials for DNA synthesis

- Synthesizes mRNA and proteins in preparation for subsequent steps leading to mitosis

- DNA replication takes place

- Protein associated with DNA are synthesized

- Chromosomes enter this phase with 1 chromatid each

- Chromosomes leave this phase with 2 identical chromatids (sister chromatids) each

- Sister chromatids remain attached by the centromere until they are separated during mitosis

- Phase located between DNA replication and onset of mitosis

- Cell synthesizes proteins, including microtubules, necessary for division

- Cell growth and cell differentiation occurs. By the end of this phase, volume of cell doubles

- Nuclear division

- Daughter chromosomes distributed by the mitotic spindle to two daughter nuclei

This describes what major phase of the cell cycle?

- Division of the cytoplasm after telophase

This describes what sub phase of the cell cycle?

___________ Molecules that influences the activities of a cell such as the cell cycle

(External and Internal)

- Growth factors signaling proteins received at the plasma membrane

Example of __________ Signals

Examples of things that happen because of ____________ Signals

- Family of proteins called cyclins that increase and decrease as the cell cycle continues

- Damage by solar radiation or X Rays repaired at the G2 checkpoint

- Family of proteins which numbers vary as the cell cycle continues

- Must be present for the cell to proceed from one stage to the next

- Without __________, the cell cycle stops at any of the G1, M or G2 checkpoints

- Programmed cell death

- Involves sequence of cellular events that bring about the destruction of the cell

- Caused by enzymes called caspases

- Opposing force to Mitosis because decreases cell number

- Fragmenting the nucleus (Cell rounds up, nucleus collapses, chromatin condenses, nucleus fragments)

- Blistering of the plasma membrane (Blebs form)

- Engulfing of cell fragments by white blood or other cells

Sequence of _______________

- Maintains homeostasis

- Abnormal cells (cancerous, virus infected) die

- Prevents damaged DNA replication

Purpose of _____________________

How apoptosis is triggered? (2 Components)

(Signaling protein ____________ activates _________________)

Cells that do not go through Cell Cycle (Stay in G0 phase - 2 types)

- Wrapping of DNA around histone proteins

- Formation of 3 dimensional zigzag structure via H1 and other DNA binding proteins

- Loose coiling into radial loops

- Tight compaction of radial loops to form heterochromatin

- _____ _____ forms with the help of a protein scaffold

This describes the formation process of ________ ________.

-Contains a single DNA molecule (double helix)

-Associated with histones (proteins)

-DNA & histones together called chromatin

-Nucleosames joined together by linker DNA appear as beads on string

-String folds into compact zigzag structure

-Loops into radial loops

-Loosely coiled

-Represents the active chromatin that can be transcribed by RNA polymerase and transcription factors

This describes the ______________ ____________

- Proteins that play structural role

- Essential survival functions

- Primarily 5 types

- Responsible for DNA packing into nucleus

- Help with gene regulation

- More highly compacted form of chromosome

- Inactive chromatin because suppressed

- Genes hardly ever transcribed

- More easily moved than extended chromatin

- Most chromosomes have both compaction levels

- Recovery phase

- Doubles organelles

- Doubles in size

- Synthesizes materials for DNA replication

- Duplicates DNA - chromosome, 1 Chromatid becomes 2 chromatids, consists of two identical double-helical DNA molecules (sister chromatids which are two strands of genetically identical chromosomes)

- Attached together at a single point called centromere

- Proteins (histones) associate with DNA

- Materials for mitosis such as proteins and microtubules are synthesized

- Cell growth

Each species has a characteristic number of ___________________________

Ex: Humans have 46

- Includes two sets of chromosomes, one from each parent

Cells can divide a limited amount of times? True or False.

Signaling protein that stops cell cycle at G1 checkpoint if DNA is damaged (Attempts repair - mitosis, unsuccessful - apoptosis)

Structural units of Chromosomes (4)

- Consisting of a segment of DNA wound in sequence around 8 histone protein cores

- This structure is often compared to thread wrapped around a spool

- DNA + Histones (Proteins)

- Lightly packed form of chromatin (DNA, RNA and protein) that is enriched in genes, and is often (but not always) under active transcription by RNA polymerase and transcription factors

- DNA + Nucleosomes

Tightly packed and folded chromatin

- Humans have ______(n) different types of chromosomes

- Each type represented twice as a pair in each body cell (diploid 2n = 46)

Sperm and eggs have one of each type of chromosome

n = 23

- Microtubule organizing center in animal centers

- Also replicated in S phase, so there are two of this before mitosis begins

- Contain two barrel shaped centrioles in animal cells that are oriented at right angles to each other

- Organizes mitotic spindle

- Contains many fibers

- Each fiber is composed of a cylindrical bundle of microtubules

- Microtubules assemble when tubulin subunits join

- _______________ fibers form when subunits disassemble or allow the cell to change shape for cell division

- In animal cells, microtubules form these star like arrays during prophase called ___________

- Nucelar division about to occur

- Chromatin condensed becomes chromosome distinguishable with microscope

- Each chromosome has 2 sister chromatids held together at centromere

- Nucleolus disappears

- Nuclear envelope fragments

- Spindle begins to assemble

- Two centrosomes move away from each other and microtubules form asters

- Preparations for sister chromatid separation

- Centromeres develop two kinetochores (a specialized protein complex, attached to each sister chromatid) to connect them to opposites poles of the mother cell

- Specialized protein complex attached to each sister chromatid during prometaphase

- Physically connect sister chromatids with specialized microtubules

- These connect sister chromatids to opposite poles of the mother cell

- Chromosomes pulled around by kinetochore fibers

- Forced to align across the equatorial plane of the cell through which mother cell will be divided

- Nonattached, polar spindle fibers overlap

- M Checkpoint delays start of anaphase until kinetochores are attached properly

This describes the phase _________

- Centromere dissolve, releasing sister chromatids

- Sister chromatids separate at the centromere

- Now called daughter chromosomes

- Pulled to opposite poles along kinetochore fibers

- Poles move farther apart

This describes the phase _________

- Mitotic spindle disappears

- New nuclear envelopes form around daughter chromosomes

- Two clusters of daughter chromosomes with all types represented, which will become daughter nuclei

- Nuclear envelopes form around daughter nuclei and each nucleus receives one chromosome of each type

This describes the phase _________

- Required for the division of the cytoplasm after telophase

- Chromosomes become diffused chromatin once again

- Allocates the mother cell's cytoplasm equally to daughter nucleus

- Often begins in anaphase and proceeds differently in plant and animal cells

This describes the phase _________

- Cleavage furrow appears between daughter nuclei

- Formed by contractile ring of actin filaments which pinches mother cell in two

This describes the cytokinesis of ___________ cells

- Begins with formation of cell plate - cell wall do not permit furrowing

- Small membrane bounded vesicles are made by Golgi

- Vesicles containing membrane components fuse into one thin vesicle across mother cell

- Membrane of cell plate become plasma membrane between daughter cells

- Space between daughter cells becomes filled with middle lamella on which primary cell walls will later by secreted

This describes the cytokinesis of ___________ cells

- Permits growth and repair

- In flowering plants, retains ability to divide throughout life of the plant

- Trees increase girth

- Fertilized cell becomes embryo to fetus, from child to adult

- Asexual reproduction

Functions of _________

- Retain ability to divide

- Ex: Red bone marrow divides into various other types of blood cells

- In most mammalian organs

This describes what type of cell?

- A method of producing human tissue with either adult stem cells or embryonic stem cells

- Involves the replication of human embryos to harvest stem cells for medical uses

- Designed as therapy for a disease

- Production of a new individual with embryonic stem cells

- Production of a genetic duplicate of an existing organism

- The abnormal growth of cells

- Two types: benign and malignant

Type of tumor that is:

- Not cancerous, encapsulated

- Do not invade neighboring tissue or spread

Type of tumor that is:

- Cancerous, not encapsulated

- Readily invade neighboring tissues

- May also detach and lodge in distant places (metastasis)

- Results from mutation of genes regulating the cell cycle, thus loss of control to cell cycle

Ability for a malignant tumor to spread to other, distant areas

- Tends to be gradual and multistep (benign, additional mutation, malignant)

- Can take years to develop

Development of ____________

- Cells are non specialized

- Do not contribute to the function of a tissue

- Cells are immortal (can enter cell cycle repeatedly)

Cancer Cells Characteristic __________________

- Cells may be enlarged

- Abnormal number of chromosomes

- Extra copies of genes

Cancer Cells Characteristic __________________

- Abnormal but fail to 'program cell death'

Cancer Cells Characteristic __________________

Mitosis is normally controlled by contact with neighboring cells (Contact inhibition) but this ability is lost in cancer cells

Cancer Cells Characteristic __________________

- Original tumor easily fragments

- New tumors appear in other organs

Cancer Cells Characteristic __________________

- Development of new blood vessels that bring nutrients and oxygen to the tumor

Cancer Cells Characteristic __________________

Difference between Cancel and Normal Cells (6)

What does the G1 Checkpoint Check for? (5)

Resting phase of nerve and muscle cells.

What does the G2 Checkpoint check for? (2)

What does the M - Metaphase Checkpoint check for? (2)

A gene that is thought to play a role in regulating cell death or apoptosis, in suppressing tumors, in regulating the cell cycle, and in stopping the cell from dividing when the DNA is damaged

A type of enzyme that play essential roles in programmed cell death, such as apoptosis.

any of a number of proteins associated with the cycle of cell division that are thought to initiate certain processes of mitosis.

Functions of Mitosis (3)

3 types of genes may be mutated which may cause cancer

- Mutation of proto-oncogene

- Normal growth and tissue maintenance depends on a balance between signals that promote and inhibit cell division, but this balance is upset

- "Gas peddle constantly pressed"

- Code for proteins which promote the cycle in various ways (genes)

- Promote progression through the cell cycle

- Include receptors and signaling molecules

Code for proteins which inhibit the cell cycle and promote apoptosis (gene)

- When inactive, may promote cancer development

- Cell cycle accelerates

- Ex: p53 genes

When ___________________ become inactive

- Cause telomeres to continue to lengthen which allows cells to continually divide, such as a cancer cell.

- Chromosome DNA folded up in nucleoid

- Replicate into two rings prior to cell division

- Replicated rings attach to the plasma membrane

- Binary fission

- Splitting of prokaryotic

- 2 replicate chromosomes are distributed to two daughter cells that are individuals that are identical to parent cell

- Called asexual reproduction

- No spindle is involved

An intestinal microbe that has a generation time of about 20 minutes

What type of organism goes through cell division by binary fission?

What type of organism goes through cell division through mitosis and cytokinesis?

Asexual production is the function of cell division for what type of organisms?

Apoptosis

A) is programmed cell death.

B) is a process that acts to decrease the number of somatic cells.

C) frees the fingers and toes of the human embryo from their ‘webbed' structure to independent structures.

D) All of the choices are correct.

Interphase

A) occupies the majority of the cell cycle

B) includes G1, S and G2 stages

C) results in an increase in cell size

D) All of the answer choices are correct.

The function ofmitosis is:

B) asexual reproduction in some species.

C) to ensure that each new cell receives a complete set of genetic information.

D) All of the choices are correct.