Ch. 3 Flashcards
Plasma Membrane
Selectively permeable phospholipid bilayer forming boundary of cells. [embedded with proteins]
> hydrophilic head with hydrophobic tails in the middle
> membrane proteins receive/bind chemical signals to cell & enzymes carry out chemical reactions
Cell Surface Extensions [4]
- Microvilli
- Cilia
- Flagellum
- Pseudopods
- Microvilli- fingerlike projections; increase surface area
- Cilia- hairlike extensions move in wavelike manor (respiratory tract & uterine tubes)
- Flagellum- tail of sperm used to move along mucous membrane of uterus
- Pseudopods- cytoplasm filled extensions; used to engulf bacteria
Cell Junctions [3]
Enables cells to grow/divide & communicate w/eachother
- Tight junction- prevent leakage of extracellular fluid
- Desmosome- holds cells together & keeps them from falling apart (skin/cardiac muscle)
- Gap junction- provide cytoplasmic channels from one cell to another
Selective Permeability
Allows some substances to pass & holds back others
Simple Diffusion (passive transport)
Movement of solute from HIGH concentration to LOW concentration; NO ENERGY NEEDED.
Facilitated Diffusion (passive)
Movement of solute from a LOW concentration to a HIGH concentration; uses carrier proteins to move solutes through membrane.
Osmosis
Movement of water from a LOW concentration to HIGH solute concentration
> Tonicity- ability of a solution to cause a cell to gain or lose water (hypo,hyper,iso)
Hypotonic (BURSTS)
Concentration of solute is HIGHER inside the cell than outside; water enters cell & bursts
Isotonic (NORMAL)
EQUAL concentration of solutes inside & outside of cell
Hypertonic (SHRIVELS)
Concentration of solute is LOWER inside the cell than outside of cell; draws water out & cell shrinks
Active Transport/Active Diffusion(energy required)
Carrier-mediated transport (needs help) going from a LOW concentration gradient to HIGH
Sodium-Potassium (Na+-K+) Pump
Controls cell volume, generates body heat & provides energy for other transport pumps
3 Na+ pumped OUT of cell
2 K+ pumped INTO cell
Vesicular Transport
- Endocytosis [P.P.R]
- Exocytosis
Requires ATP & moves through membrane in vesicles
1. Endocytosis-brings matter INTO cell
>Phagocytosis- “cell eating”
>Pinocytosis- “cell drinking” & pinch off as vesicles
>Recepter-mediated-takes in specific molecules from specific receptor proteins
2. Exocytosis-releases matter OUT of the cell
Cytoskeleton [Protein filaments & tubules]
- Microfilaments- thinnest, made of protein ACTIN; fibrous mesh “terminal web”
- Intermediate Filaments- tough protein KERATIN; strength of desmosomes
- Microtubules-thickest, holds organelles in place & maintains cell shape
Nucleus
Largest organelle; genetic control center of a cell
Rough Endoplasmic Reticulum
Protein synthesis; interconnected cisternae (channels); cisternae covered with ribosomes
Smooth Endoplasmic Reticulum
Lipid synthesis; detoxification; calcium storage
Ribosomes
Protein & RNA; produced in the nucleus—>moved to cytoplasm, assemble amino acids into proteins
Golgi Complex
Packages products in golgi vesicles to become lysosomes
Lysosomes
Contain enzymes; round/oval; apoptosis-cell death
Peroxisomes
Produce hydrogen peroxide; break down fatty acids; detox free radicals
Mitochondria
Synthesize ATP; inner folds are cristae (holds enzymes for ATP); mDNA (small dna) is the space between cristae
Centriole
Aids in cell division (mitotic spindles); cylindrical assembly of microtubules
Centrosome
Area of cytoplasm near the nucleus containing a pair of centrioles
Protein Synthesis (T & T)
- Transcription- 1st step; occurs in nucleus; synthesis of an RNA molecule from DNA
- Translation- 2nd step; occurs in cytoplasm; process by which mRNA is decoded and a protein is produced
Cell Cycle
G1-S-G2-P-M-A-T-C
[INTERPHASE]
G1- 1st gap phase, make filaments/replicate centrioles, growth & normal metabolic rates
S-synthesis phase, replicated DNA (2pairs) & unzips polymerase
G2- 2nd gap phase, finishes centriole replications, growth & preparation
[M-MITOTIC PHASE]
Prophase- Chromatin thickens to chromosomes & spindle fibers form
Metaphase- Chromosomes align in the middle of the spindle fibers
Anaphase- Pair of chromosomes (sisters) pull apart & move to opposite sides (daughter chromosomes)
Telophase- Spindles disintegrate; nuclear membranes form; chromatids turn back into chromatin & cluster on each side of the cell
Cytokinesis- division of cytoplasm; pinches into two & new cells begin interphase & cell cycle begins again.
