Unit 4 Flashcards
what is cell division for
reproduction of cells, growth of cells, tissue repair
Condensed chromatin
Chromosomes
non condensed chromosomes
Chromatin
Genetic information is only in chromosome form during
Cell division
When does chromatin condense
After dna replication
Centromere definition??
Region on sister chromatids where they are most closely attached
Kinetochore definition??
Part in chromosome where the spindle fibers attach
What’s a genome?
All of a cells genetic information
How do prokaryotes have their dna
Singular circular dna
How do eukaryotes have their dna
One or more chromosomes
Humans have how many chromosomes?
46
Homologous chromosomes are?
Two chromosomes that are the same length, have same centromere position, and have genes controlling same characteristics
Order of cell cycle?
G1 -> S -> G2 -> Mitosis
G1, S, and G2 are all in
Interphase
What happens in G1
Cell grows and does normal things
What happens in S
DNA replicates
What happens in G2
Final growth, preparation for mitosis
Mitosis results in……
2 identical diploid daughter cells
Order of mitosis steps?
Prophase, Metaphase, Anaphase, Telophase & Cytokenesis
What happens in prophase?
Chromatin condenses, centrosomes appear
What happens in metaphase?
Chromosomes go in middle, they’re connected to centrosomes
What happens in anaphase?
Chromosomes are pulled apart by centrosomes, sister chromatids separate and move to opposite ends of cell
What happens in telophase and cytokenesis?
Two nuclei form, chromosomes uncondense
G1 Checkpoint
Most important checkpoint
Checks for cell size, growth factors, and DNA damage
What happens if G1 checkpoint says stop?
Cell enters G0
G2 Checkpoint happenings
Completion of DNA replication checked
DNA damage checked
What happens if G2 checkpoint says stop?
Cell cycle stops and the cell will try to repair damage, if it cant, the cell will undergo apoptosis
M Checkpoint happenings
Checks for microtubule attachment to chromosomes at metaphase
What happens if M checkpoint says stop?
Cell pauses mitosis to allow for spindle fibers to finish connecting to the chromosomes
Cell cycle is regulated by ?
Cyclins and cyclin-dependent kinases CDKS
Cyclins are?
Only in the cell cycle at certain points
Proteins
Cyclin-dependent kinases are?
Constant throughout cell cycle
Enzymes
Active only when it’s specific cyclin is present
Uncontrollable growth of cells =
Cancer
Metastasis?
When cells separate from cancerous tumors and go throughout the body
What are set points?
Values for various physiological conditions that the body tries to maintain
What is normal range?
The range a set point can fluctuate
What’s homeostasis?
The state of relatively stable internal conditions
How does the body maintain homeostasis?
Feedback loops
What’s a stimulus?
A variable that will cause a response
What’s a receptor?
Sensory organs that detect a stimulus
What’s an effector?
The muscle or gland that responds after messages are sent to brain
Negative feedback?
The goal is to stop the thing that started it. Ex: heat causes sweating, goal of sweating is to stop you from being hot
Positive feedback
The goal is to increase the thing that started it. Ex: child birthing, signals are sent to child birth harder
Disease is
When the body can’t maintain homeostasis
How do cells communicate?
Direct contact
Local signaling
Long-distance signaling
How are signals sent in direct contact?
Through cell junctions
Cell junctions in animal cells?
Gap junctions
Cell junctions in plant cells?
Plasmodesmata
Local signaling
One cell sends out some signal molecules, other cell picks them up
Causes response in TARGET CELL
Kinds of local signaling?
Paracrine signaling
Synaptic signaling
Paracrine signaling
Secretory cells release local regulators via exocytosis to an adjacent cell
Synaptic signaling
Neurons release neurotransmitters from axon terminals through exocytosis into a synaptic cleft, diffuse across synaptic cleft, neurotransmitters bind to receptors on the dendrite of another neuron
What do plants and animals use for long distance signaling?
Hormones
How do plants do long distance signaling?
Release hormones that travel in plant vascular tissue (xylem and phloem) or through the air to reach target tissues
How do animals do long distance signaling?
Endocrine signaling, cells release hormones into circulatory system (bloodstream) where they reach target cells
First step of cell signaling?
Reception: ligand binds to receptor and undergoes conformational change
Second stage of cell signaling?
Transduction: extracellular signal is converted into intracellular signal, usually also amplified
Third step of cell signaling
Response: cell process is altered
All receptors have?
An area that interacts with the ligand and an area that transmits signal to another protein
Binding between ligand and receptor is
Highly specific
When the ligand binds to receptor
Transduction signal initiates
Where can receptors be?
In the plasma membrane or intracellular
During transduction
Signal is amplified using second messengers
Signal transduction pathways can
Result in changes to gene expression
Result in apoptosis
Mutations to receptor proteins cause
A change to the transduction of the signal
G protein coupled receptors are
Largest category of cell surface receptors
What happens in G protein coupled receptors?
Ligand binds to GCPR on extracellular side, cytoplasmic side changes shape, G protein binds to GPCR, G protein activates enzyme, signal amplified
Ion channels are
Located in plasma membrane
Important in nervous system
What happens in ligand gated ion channels
Ligand binds to ion channel protein, it opens up, molecules go through, molecules activate enzyme, enzyme does transduction
