Unit 4 - AP Biology

Cell communication purpose (3)

• Autoimmunity

• Reproduction

• Homeostasis

Types of cell communication (3)

• Direct - cell to cell via shared cytoplasm (channels/junction) or surface receptors

• Local regulators - short distance chemical messages to nearby cells

  • keywords: surrounding, nearby

• Long distance signaling - using hormones, can travel to multiple areas

Types of local regulators (2)

Paracrine signal - using regulatory molecules that as a signal to neighbor cells

Synaptic signal - using neurotransmitters thru axons/nerves to signal other neurons

Types of long distance signaling (2)

Chemical signaling - plant based hormones thru xylem/phloem to tissues

Endocrine signaling - animal based hormones thru blood to gain a response from specific cells

Stages of cellular communication (3)

1. Reception

2. Transduction

3. Response

Reception

When a stimulus/signal is received by the cell via it binding to the receptor protein

Ligand

Signaling molecule that can bind + changes a receptor proteins shape to be a intercellular signal

• (what’s going on outside?)

Types of ligands (2)

• Hydrophilic - molecules that bind to a MEMBRANE RECEPTOR

• Hydrophobic - molecules that bind to a receptor INSIDE THE CELL by passing the membrane

  • transcription factors, steroid (lipid) hormones

Types of hydrophilic ligands (3)

1. G-protein coupled receptors - activates g proteins that initiate a cellular signal

2. Receptor tyrosine kinases - activates phosphorylation for cell division, targets proteins

3. Ligand gated ion channels - channels that allow in ions after a ligand binds onto receptor

Transduction

regulatory pathways that cause cellular responses

• extracellular → intracellular signals

Phosphorylation cascade

When addition of phosphates triggers chain reaction of activating protein intermediates till the protein for a response is activated

Kinase

enzymes that add phosphate to activate signals to intermediates

Phosphatase

enzymes that REMOVE phosphate to deactivate signals to intermediates

Second messengers

NONPROTEINS that amplify responses from transduction- can assist activating kinases

• cyclic AMP

Response (3)

regulation of cell processes.. including

• activating proteins/enzymes

• gene expression

  • membrane permeability

  • cell growth

  • cell division

  • cell differentiation → specialization of genes

  • apoptosis

Process of cellular communication (4)

1. Ligand binds with receptor to create signal

2. Phosphorylation cascade is triggered; kinases activate proper proteins needed until

3. Kinase enters the nucleus activating transcription factors for the gene required for response

4. Genes will synthesize the REQUIRED PROTEIN for the FINAL response of the cell (outside)

Feedback (2)

communication between cells/organs for a response

• Negative - inhibition

• Positive - enhances

Stimulus, receptor, effector, response (what is all of these?)

Stimulus - causes response

Receptor - detects stimulus

Effector - increase/decrease stimulus effect

Response - handles stimulus

Interphase (3)

LONGEST phase of a cell cycle

• G0 (default) → G1 (intending to divide, replenish organelles)

• S - DNA synthesis

• G2 - prep for mitosis, duplicate centrosomes

M Phase

Mitosis + cytokinesis occurs (PPMAT)

Chromatin vs chromosomes

Chromatin - DNA w histones, default form of DNA in nucleus = interphase

Chromosomes - condensed units, 1-2 sets of chromosomes = M phase

Haploid vs diploid

Haploid - one set of chromosomes (2 total) - in GAMETES/sex cells/meiosis

Diploid - two sets of chromosomes (4 total) in SOMATIC/body cells/mitosis

Sister chromatid

Duplicated chromosomes (2)

Centromere vs kinetochore

Centromere - center of chromosome that keeps chromatids together

Kinetochore - protein that allows spindles to attach to the centromere to pull the chromosome apart

Stages of cell division/M phase (6)

1. Prophase

2. Prometophase

3. Metaphase

4. Anaphase

5. Telophase

6. Cytokinesis

Prophase (3)

• Nucleus dissolves

• Chromosomes condense

• Centrosomes seperate to make spindles

Prometophase

Spindles dome over chromatids

Metaphase

Centrosomes align on polar ends of the cell, aligning chromatids to the MIDDLE

Anaphase

Spindles pull apart the chromatids from the centromere to the ends of the cell

Telophase (2)

• New nucleuses form on each side, taking the chromatids to uncondense into chromatin

• Removes spindles

Cytokinesis (2)

• Animals - form cleavage furrow to split into two new cells

• Plants - form cell plate to merge the cells to form a grid

What regulates the cell cycle? (3)

• Cyclins - signals cell division

  • Cyclin dependent kinase - activate proteins w cyclin

• Growth factor - proteins to make other cells do mitosis

  • Only will if enough space or cells are anchored

• Checks between phases (interphase → m phase)

  • is it G1? is there no mutations in S? is chromatids aligned and attached in M?

Positional inhibition (2)

Ability of cell cycle regulation in growth factors.. will work if

• Density dependent - is there enough space

• Anchorage - are the cells locked on a area

Cancer

Uncontrolled cell division that act w/o or make their own growth factors, routing blood vessels for nutrients (angiogenesis)

Benign vs malignant

Benign - mass of cells with no effects

Malignant - mass of cells that can spread by moving in the circulatory system (metastasizing)

Proto-oncogenes vs tumor suppressor genes

Proto-oncogenes are made up of mutated Ras proteins that overproduce cyclin

Tumor suppressor genes are p53 mutated to not inhibit mitosis

Causes of cancer (4)

• Genetics

• Viruses - damage regulatory genes

  • HPV

• DNA damage (UV, radiation)

• Mutations

Cancer treatments (3)

• Chemo

• Radiation

• Surgery