smallest functional unit of an organism
functions of the cell (4 total)
- 1) exchange materials with immediate environment
- 2) obtain energy from organic materials
- 3) synthesize complex molecules
- 4) replicate themselves
what is a eukaryotic cell
one that has a true nucleus
contains DNA necessary for protein synthesis and survival. Contains chromatin a genetic material used for replication. Nucleus also contains chromosomes and an envelope that surrounds it that contains pores
Nucleus synthesizes what?
3 types of RNA 1) Messenger 2) ribosomal and 3) transfer
it is a colloid solution
ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, perioxisomes, proteasomes, and mitochondria
site for protein synthesis
2 types rough ER and smooth ER
it functions with the endoplasmic reticulum. It packages proteins, enzymes, and hormones.
contain digestive enzymes. Break down cell parts and foreign substances, some "residual bodies" are retained.
quality control mechanism
POWER PLANT of the cell. it transforms organic compounds into energy. it is self-replicating via mitochondrial DNA. It is also a regulator of apoptosis (programmed cell death)
maintains cell shape. Inside contains microtubules that maintain shape and enable transport. Also contains microfilaments that are threadlike structures.
defines the intracellular space. contains a semipermeable membrane.
function of the semi permeable membrane of the cell membrane
- 1) controls transport of water and substances
- 2) provides receptors for hormones
- 3) conducts electric currents
- 4) enables cell to cell recognition
anatomy of the cell membrane
- Lipid bilayer: hydrophilic heads and hydrophobic tails
- this allows lipid soluble molecules to diffuse easily.
- Proteins also extend across the bilayer. Glycoproteins: are cell surface markers and recognize and bind with ligands
- cell receptors activated by chemical messengers
- types of cell signaling mechanisms
Cell reproduction (the cell cycle)
- Go: inactive phase
- G1: start of DNA synthesis
- S phase: DNA replication
- G2: RNA and protein synthesis
- M phase: mitosis
phases of Cell mitosis
- prophase: appearance of chromosomes
- Metaphase : organization of chromosomes
- anaphase: separation of pairs
- telophase: cells separate
how long does a cycle of cell division take??
how do cells change through the lifetime???
- all cells undergo mitosis during embryonucu development. Many adult cells lose the ability later on.
- epithelial cells divide continuously
peptides which signal division. specific to cell type for example nerve cells respond to nerve growth factor.
- conversion of nutrients into energy needed for cell function.
- cells use oxygen to transform nutrients into energy for 1) muscle contraction 2) ion transport across membranes 3) synthesis of hormones, enzymes, etc...
Adenosine Triphosphate (ATP)
carrier for chemical energy in living cells
ATP is composed of
- adenosine, ribose, and 3 phosphate groups.
- Each molecule contains 2 high energy bonds
- Each bond releases energy when hydrolyzed into ADP
what are the two types of energy production used in the body?
Anaerobic and Aerobic
Anaerobic Metabolism and Glycolysis
- glycolytic pathway which occurs in the cytoplasm.
- Energy is liberated from glucose
- one molecule of glucose yields 2 ATP
- Very important during hypoxia
- when O2 is present, pyruvic acid moves into the mitochondria and enters the citric acid cycle
Aerobic metabolism and citric acid cycle
- supplies most of the bodies energy
- pyruvic acid converted to acetyl-CoA
- H+ and carbon molecules combine with O2 to form CO2 and H2O.
- Oxidation of electrons
- Oxidative phosphorylation
Membrane Transport mechanisms
- channel proteins
- membrane transport proteins, may use a carrier
- electron potentials across all cell membranes
- determined by differences in ions on inside vs outside
- resting membranes potential maintained by Na+/K+ pump
- Na+ channels
- calcium channels
- repolarization and K+ channels
- absolute refractory period
- relative refractory period