G1
Growth
-Protein Production
-Organelle Production
Cyclin checkpoint D- moves the cell to G0
S
synthesis, DNA replication
Cyclin Checkpoint E- Prepares for S and allows it to start
Cyclin Checkpoint A-(end of s) starts replication
G2
Some growth
-Prepares for division
-Replicates Organelles
Cyclin Checkpoint B-starts M phase ( mitosis or meiosis)
Prophase
Duplicated chromatin will super-coil or condense into chromosomes. Then, the chromosomes will pair up into sister chromatids.
-Centrosomes will release centriols and will move to the opposite poles and begin to create the mitotic spindle.
-Nuclear envelop
Metaphase
-macrotubules from the mitotic spindle will connect to the kinetochores, at the centromere.
-contraction of the spindle fibers(microtubules) will align the sister chromatids along the equator.
Anaphase
-Kinetochore will contract to separate the sister chromatids into chromosomes.
-Centriols will push out on the cell membrane in preparation of telophase.
Telophase
-Centriols will push to lengthen cell.
-Chromosomes will arrive at the poles
-Mitotic Spindle will dissolve
-nuclear envelope begins to reform around the separated chromosomes
-Chromosomes decondense back to chromatin.
Telophase (Animal Cell)
Microfilaments inside the membrane pulls toward inside. This creates a cleavage furrow. When the furrow reaches the center, the cell is pinched apart.
Telophase (Plant cell)
Vesicles deposit proteins to create the "cell plate". Once the cell plate reaches either or both sides, the two cells secrete cellulose to form the cell wall.
Cytokinesis
division of the cytoplasm . Can occur sometimes simultaneous
Reception
Signaling molecule is recognized and received by receptor protein
Transduction
Converts into recognized form for the cell.
ligand
type of molecule that specifically binds to another (lock and key, or induced fit)
Receptor
what the ligand binds to( type of membrane) usually transmembrane
What are the possible locations for a receptor
either on the cell membrane or intracelluar (cytoplasm or nucleus
Why are transmembrance receptors needed
Many ligands or signaling molecules cannot pass through the membrane alone, usually large. Also, receives from extracellluar space.
What is the process of G-protein linked receptor?
A ligand binds to the receptor. The recptor activates the G-protein which will carry GTP to an enzyme. The enzyme will then activate, using the energy from GTP, to elicit a celluar response. The ligand or signaling molecule will detach and the GDP is sent
What activates a G protein
The receptor once activated by the ligand/signal
How are ions transferred by the process of voltage-gated pathway?
1. The gate is closed. no flow of ions
2. Gate opens when a ligand binds and allows specific ions to enter the cell. This rapidly changes the concentration in the cell to elicit a response.
3. Ligand is removed; gates closes. No more flow of ions
In what body system are ligand-gated ion channels and voltage-gated ions of particular importance?
NERVOUS SYSTEM
Nearly all nerve response occurs this way.
Protein Kinase
The enzyme that transfers phosphate groups from ATP. Used in cascade fashion (one after another) to elicit a cellular response (like in the cell cycle)
protein phosphatases
An enzyme that rapidly removes phosphate groups from activated kinases to then inactivate them.
What is a difference between a first messenger and a second messenger?
1st- signal molecule which attaches to a membrance receptor.
2nd- small, nonprotein water soluable molecules ( or ions) that can diffuse rapidly through the cell to activate kinases in the cytoplasm.
When cell signaling causes a response in the nucleus, what normally happens?
Usually activates/regulates protein synthesis using transcription factors. Can turn genes on or off and synthesis of mRNA for a specific gene.
When cell signaling causes a response in the cytoplasm, what normally happens?
Sometimes activates gene expression or opens/closes specific ion channels.
Immune
white blood cells communicate with each other when a pathogen/antigen is identified.
T cells
initial antigen recognizer
-"helper":notify B cells when to produce antibodies
-"cytotoxic":will bind to a pathogen and destroy the cell.
B cells
secrete antibodies
-specific to an antigen
Neurotransmitters:
Nerve cells
-Voltage-gated pathways ( +- )
Action potentials used to reinforce. Positive feedback. to send signal to/within a cell. Negative feedback is used to stop it.
resting potential-> active potential is changed by positive or negative ions
Nerve ce
Hormones: regulate signal pathways
Insulin is used to "unlock" the glucose channels in the intestines to allow the uptake (absorbtion) of glucose. Made in Pancreas. Lower blood glucose- Negative feedback
How does the genome of a prokaryotic cell differ from that of an eukaryotic cell
Prokaryoticss-binary fission, single free-floating + circular . No histone proteins
Eukaryotes are anti-parallel strands( multiple) histone proteins present
Chromosome
condensed DNA (supercoiled) DNA isn't lost
Chromatid
Replicated chromosomes --> S
Centromere
holds sister chromatids together
Chromatin
relaxed/decondensed DNA ( Interphase G1)
What is the difference between mitosis and meiosis
mitosis-genetically identical
meiosis- variety( 2 stages) non-identical
Centrosomes
contain two centriols which produce the mitotic spindle. Centrosomes release centriols which move to opposite poles.
What is the role of kinetochores and the microtubules?
The spindle fibers or the microtubules attach to the kinetochore at the centromere.
Eukaryotic mitosis is thought to have evolved from....
Bacterial Binary fission
-Some unicelluar eukaryotes illustrate a possible "intermediate step.
G1 Checkpoint
E Cyclin- allows S to start
G2 checkpoint
A Cyclin- checks and proceeds replication into G2
M checkpoint
B cyclin- allows mitosis to start
G0 phase
Rest stage. There is no growth and no divining. Most human SOMATIC cells are in this stage. Some may leave in situations such as injury.
Why is the regulation of the cell cycle critical to normal cells?
Uncontrolled cell growth leads to cancer. (tumor)
Kinase:
enzymes that will activate or inactivate phosphorylation.
Cyclin:
proteins that perform the "checkpoint" stages and interacts with kinases.
What are the two normal behaviors that cancer lacks
1. density-dependent inhibition .
2. Anchorage dependence
density dependent inhibition
cell growth and division is stopped when cells become "crowded" close together
anchorage dependence
must be attached to a substrate to divide such as extracellular tissue.
What is transformation? Metastasis?
Able to divide indefinitely/continous
Metastasis- spread of cancer cells to distant locations
Explain what occurs in cell differentiation and morphogensis
Cell differentiation- cells become specializied in structure and function
Morphogensis- overall shape
Differential gene expression results from different activators in different cells. How do different sets of activators come to be present in two cells? Explain how each of these occurs:
*Distribution of cytoplasmic determinants-beginning to development where mitosis distributes cytoplasm.
*Different inductive signals-cause changes in the cell that receive them. During early mitosis
What is meant by determination? Explain what this means within an embryonic cell
The intended type of cell.
Once differentiation changes a cell past its threshold, it will always develop into that cell.
What is apoptosis and how does it play a role in development?
Programmed cell death"
Once cells reach their end of their life, they will be broken down.
What process ensures that all the tissues and organs of an organism are in their characteristic places? Where do the molecular cues that control this process arise?
Pattern Formation-literally where "stuff" develops in an organism. Positional information ( the cues) are indicated by determination and induction.
What is controlled by homeotic genes?
genes that control pattern formation
How is nuclear transplantation performed in animals?
SCNT/SCNC -> Somatic cell Nuclear Transplantation
-Remove nucleus from egg and replace with differentiated Somatic cell. Best for young donors
What are stem cells? What is the major difference between Embroynic Stem cells (ES) and adult stem cells?
Stem cells- undifferentiated or unspecialized cells
ES- develops into many different cells ( totipotent)
AS-only can develop into the previous specialized cell.
What mechanism is involved in the beginning of tumor growth? Discuss oncogenes and proto-oncogenes and how they are converted?
Cell cycle regulation errors= tumors
oncogenes-genes that cause cancer
proto-oncogenes-normal versions of oncogenes( potential to cause cancer)
Genectic changes( mutations, carcinogens, replication errors) can change proto --> oncogene.
Describe the double whammy that results from mutation of p53
p53 is a regulator of the cell cycle. Once mutated it can no longer stop growth. p53 can also activate other genes that will no longer inhibit growth.
Explain the multistep model of cancer development and compare it to the embryonic development
1. Loss of tumor-suppressor
2. Growth continues
3. Activation of Oncogenes
4. Loss of p53
5. Growth continues with high chance of mutations
6. Mutations lead to Malignant tumor- that can spread to other parts of the body
benign- tumors that cannot spread
totipotent stem cells
can differentiate into any type of cell
Pluripotent stem cells
can differentiate into similar cell groups
Unipotentstem cells
Only one cell typle. Adult stem cells
signal tranduction pathway steps
Ligand --> receptor--> relay protein --->amplification--> response
What advantage would there be in an organism if the signal tranduction pathway had several amplication steps?
1 receptor can activate several responses in the cell. Can activate different signal pathways.