Chapter 3 - Cellular Level of Organization Flashcards
2 Types of cells
somatic and sex
Cell membrane
physical barrier, and provides structural support
Membrane Structure
a phospholipid bilayer that keeps the composition inside and outside the cell different. A very selective hydrophilic heads and hydrophobic tails.
Membrane Proteins
Anchor one cell to another, recognize neighboring cells, enzymes, hormone receptors, carrier proteins, channels, and electron transferers.
Peripheral proteins
attached to the inner or outer surface of the membrane
Integral proteins
part of the membrane structure
Membrane Permability
passive - movement without energy; active - movement what requires energy, usually ATP.
Diffusion
Passive; involved distance, size, temperature. Movement direction depends on concentration
Osmosis
Diffusion of water that goes from an area of higher concentration to a lower concentration. It involves pressure called osmotic pressure.
Isotonic
The concentration in an d out of the cell is the same
Hypotonic
Higher concentration outside the cell, water toxification.
Hypertonic
Higher concentration inside the cell, dehydration
Filtration
movement across a membrane, that depends on pressure and size of pores in that membrane
Facilitated Transport
Carrier proteins transport solutes, channel proteins
Active Transport
Uses energy, important in transporting ions, ex: the sodium/potassium pump.
Endocytosis
Substances are imported into the cell.
Pinocytosis
The cell “gulps” a drop of extracellular fluid with solutes into vesicles.
Receptor Mediated Endocytosis
substances bind to receptor proteins enabling the cell to ingest specific substances in protein coated vesicles.
Phagocytosis
the cell engulfs a large particle by forming projectile pseudopods around it and enclosing it in a membrane
Exocytosis
Substances are exported from the cell
Cytoplasm
Material found in the cell but outside the nucleus, high in K+, low in Na+, water, high in proteins and lipids, low in carbohydrates.
Microfilaments
Protein strands mostly actin,they are involved in cell motility. Found in muscle cells and mobile cells
Intermediate filaments
provide support to help maintain the shape of a cell. tough insoluble protein fibers constructed like woven ropes
Thick filaments
Bundles of myacin protein subunits, found only in muscle cells
Microtubules
found in all cells, has the protein tubulin forming the primary components of the cytoskeleton. Gives cell strength, helps anchor cells and major organelles, and is involved in cell division.
Microvilli
Projections of the cell membrane that increase the surface area
Centrioles
Barrel shaped; composed of microtubules found in 9 groups of 3. Found in cells that divide forming the spindle apparatus
Centrosome
cytoplasm surrounding the centrioles
Cilia
9 pairs of microtubules forming very short projections whose sole purpose is to move matrial over the surface of the cel.
Flagella
Long projection made of microtubules that moves the cell, ex: sperm
Ribosomes
Assemble amino acids into proteins. Free - floating through the cytoplasm. Fixed - attached to the rough edoplasmic reticulum.
Mitochondria
Double membranes organelle that produces energy (ATP) from carbohydrates, especially glucose.
Endoplasmic Reticulum
Intracellular membranes connected to the nuclear envelope.
Smooth ER
Synthesize lipids, steroid hormones, glycerides, and glycogen. Detoxification of drugs and toxins. Storage of calcium and large molecules.
Rough ER
Outer surface has ribosomes, where proteins are synthesized then transferred to the golgi apparatus and into the transport vesicles.
Golgi Apparatus
Flattened discs called saccules. Most stacks lie near the nucleus and the ER because of the necessary communication. Synthesize and package proteins and secretions for exocytosis and for the cytosol.
Lysosomes
Vesicles from the golgi apparatus containing enzymes. they break down food, debris, and bacteria. they also break down bone to release calcium.
Peroxisomes
Smaller than lysosomes, carry different enzymes and derive from the ER. They’re most abundant in liver cells because they either remove or neutralize toxins. They oxidize free radicals.
Nucleus
Control center of the cell
Nuclear Envelope
A phospholipid double membrane separated by a perinuclear space. Made up of nucleoplasm and nuclear matrix
DNA
contains hereditary information; found in the chromosome. Wrapped around proteins called histones, forming a complex known as a nucleosome. When DNA is not dividing, it is in thread-like strands called chromatin
Nucleoli
Nuclear organelles that synthesize ribosomal RNA (rRNA)
Genetic Code
The triplet code; consists of 3 bases, each gene contains all triples needed to produce a certain protein
Transcripltion
transfer of information from a DNA base sequence to the complementary base sequence of an mRNA molecule. Happens in the Nucleus
Initiation
DNA unwinds and content segment is exposed
Elongation
RNA polymerase tracels along DNA strand, moving from triplet to triplet. Making a mRNA strand.
Termination
At a stop signal, transcription ends, mRNA is edited to get rid of introns and enters the cytoplasm
Translation
The language of nuclei acids is translated into the language of proteins. In the cytoplasm
Translation Sequence
- mRNA bings to the light ribosomal unit and scans for the strat codon (AUG)
- Anticodon is brought by the tRNA (UAC) and the heavy ribosomal unit attaches to the light leaving the mRNA to slip throught the gap in the two.
- Enzyme breaks the link between the tRNA and its animo acid in the P-site.
- The amino acid is bonded to another one the next one by a peptide bond.
- Continues until the mRNA reaches a stop codon (UGA, UAA, UAG)
Polyribosomes
a series of ribosomes attached to the same mRNA strand producing many proteins at the same time.
Meiosis
Cell divisiton producint gametes or sex cells
Mitosis
Cell division producing clones. Essential for growth and tissue repair. Continuous in some tissue, like the skin, intestinal tissue. None in the nerve tissue, skeltal muscle, or cardiac muscle.
Interphase
G0) The cell is not dividing, not in mitosis, normal cell function.
G1) Manufacturing material that is needed to divide, centriole replication begins.
S) chromosomes duplicate
G2) More preparation for division, protein synthesis, centriole replication is completed.
Prophase
Early) Two copies of each chromosome with a centromere in the middle surrounded by a protein complex called kinetochore. Nuclear envelope fragments and centrioles move to opposite poles with spindle fibers in between.
Late) Nuclear envelope disappears
Metaphase
Chromatids are moving towards the middle
Anaphase
Centromeres of the chormosomes split. Each chromatid becomes a chromosome. Cytokinesis begins very late in this phase. Shortest phase.
Telophase
Begins when the choromosome movement stops. They uncoil to form chromatin. New nuclear envelope forms, nucleoli reappear, spindle disappears. Cytokineses with full division of cytoplasm is completed
Differentiation
The process of forming specialized cells and tissues
Tight Junctions
Adjacent integral proteins that fuze the cells. Prevent liquids and most molecules from moving between the cells
Desmososmes
Transmembrane proteins that rivot the cells together at the plasma membranes cementing them together, making them very strong. Found in skin layers and cardiac muscle.
Gap Junctions
Channel proteins forming pores, connexons, allowing small molecules/ions to move the cell to cell. Important in cardiac muscle and smooth muscle because it moves the action potential.
