Ch.3 The Cell Flashcards
Cell type
form of cell fits its function
Cell
basic building block of living organisms
3 parts:
- nucleus
- plasma membrane
- cytoplasm
Nucleus
- contains DNA that builds all proteins of cell
- some multinucleate
chromosome organization:
tightly wound = inactive
loose and uncoiled = active
nuclear envelope
- part of nucleus
- membrane around nucleus
-DNA can’t cross it
nucleolus
- part of nucleus
- site of rRNA synthesis
chromatin
- unwound DNA in the nucleus
nuclear pore
- part of the nucleus
- opening in nuclear envelope
- allows mRNA out of nucleus
cytoskeleton
- different types
- internal scaffolding for cell
cytoplasm
- semi solid substance
- fills space between plasma membrane and nucleus
- composed of organelles suspended in cytosol
plasma membrane
- outer boundary of cell
- lipid bilayer
- regulates what enters or leaves the cell
ribosomes
- composed of rRNA and proteins
- site of mRNA translation
- free ribosomes are in cytoplasm
- fixed ribosomes stud outside of RER
rough endoplasmic reticulum (RER)
- network of channels
- site of protein synthesis
- ribosomes attach to its outer surface
transport vesicle
- membrane-bound vesicle
- transports substances throughout the cell
golgi apparatus
- forms stack of plates
- proteins packaged for secretion
centriole
- paired organelle
- organizes spindle fibers during mitosis
smooth endoplasmic reticulum
- forms tube-like structure
- site of lipid synthesis
lysosome
- membrane-bound vesicle
- contains digestive enzymes
mitochondrion
- bean-shaped
- site of ATP synthesis
7 characteristics of Plasma membrane
- physcally separates: interior of cell from external environment
- receives info about changes in environment
- regulates: transport + communications with other cells
- forms compartments to allow separate functions
- participates in biochemical reactions
- selectively permeable
- controls volume and internal composition cell’s and molecules
Phospholipid
- make up cell membrane
- structure: glycerol, 2 fatty acids, phosphate group and organic group
- amphipathic: hydrophilic phosphate head and 2 hydrophobic tails
Cholestrol
plasma membrane
- rigid ring lipid
- randomly distributed throughout hydrophobic region
- gives plasma membrane structural strength
Carbohydrate chains
plasma membrane
- extend from outer surface
- attached to protein or phospholipid
- functions as a signal, coating or recpetor
Extracellular environment
plasma membrane
outside of the cell
-aqueous
Phosphate group head
Plasma membrane
- part of phospholipid molecule
- makes this portion of molecule polar and hydrophilic
Fatty acid tails
Plasma membrane
- part of phospholipid molecule
- tails consist of two fatty acid chains
- makes this portion of molecule nonpolar and hydrophobic
Peripheral protein
plamsa membrane
- does not extend across lipid bilayer
- serves as anchor point for cytoskeleton
Transmembrane proteins
Plasma Membrane
- extends all the way through the lipd bilayer
- may serve as a transport protein or channel across the bilayer
functions of membrane proteins
- anchoring: anchor cell to extracellular matrix
- transport materials: passive and active transport
- act as enzymes: to catalyze reactions in membrane
- receptors: bind with signal molecules to transmit info into the cell
- recognize cells: function as identification tags
- structurally link cells: cell adhesion proteins attach membranes of adjacent cells
Cell junctions
- tight junctions
- desmosome
- gap junctions
tight junction
Cell junction
single layer of epithelial cells between two cells
desmosome
Cell junction
- strong adhesion between cells during mechanical stress
- multiply layers of epithelial cells
gap junction
Cell junction
connecting cytoplasm for fast transport
types of passive transport
- simple diffusion
- facilitated diffusion
- osmosis
types of active transport
- primary
- secondary
- vesicular
diffusion
- net flow of substance down its concentration gradient
- high to low concentration
- kinetic energy
- NO metabolic energy
simple diffusion
passive transport
- molecules or ions move passively
- down concentration gradient
facilitated diffusion
passive transport
- specific transport proteins move solutes
- Ex: 1) glucose binds to GLUT1 2) GLUT1 changes chape and glucose is released into the cell 3) GLUT1 returns to original shape
- down concentration gradient
Osmosis
passive transport
- type of diffusion
- movement of H2O through selectively permeable membrane
- from high to low H2O concentration
isotonic solution
equal solute concentration
hypertonic solution
- solute concentration outside cell is higher than inside
- cell loses water to surroundings –> cell becomes dehydrated and shruken
hypotonic solution
- solute concentration outside is lower than inside
- water enters cell –> cell causes cell to swell
primary active transport
- 2 ions move in opposite directions but from low to high concentration (against concentration gradient)
- antiport
- cell uses metabolic energy
- Ex: sodium-potassium pump
sodium-potassium pump
- uses ATP to pump 3 sodium (Na2+) ions out and 2 potassium (K+) ions in
- antiport
- low to high concentration for Na2+ and K+
secondary active transport
- carrier protein cotransports (in same direction) 2 solutes
- 1 solute down its concentration gradient –> high to low
- 1 solute against its concentration gradient –> low to high
- ATP-powered pump: maintains concentration gradient
Exocytosis
- materials exit cell
- vesicular
Endocytosis
- materials enter cell
3 types of endocytosis - phagocytosis
- pinocytosis
- receptor-mediated endocytosis
Phagocytosis
- large particles enter cell
1) folds of plasma membrane surround particle to be ingested forming small vacuole around it
2) Vacuole then pinches off inside cell
3) lysosome fuse with vacuole
Pinocytosis
- dissolved materials enter cell
Receptor-Mediated Endocytosis
- Substances (like LDL) attach to specific receptors in coated pits on plasma membrane to enter cell
- uncoated vesicle fuses with endosome
- Receptor recycled to plasma membrane
- endosome fuses with lysosome and dissolves into free cholesterol
Eukaryotic cell division
- Interphase
- G1: 1st gap phase
- S: Synthesis phase
- G2: 2nd gap phase - M phase: mitosis and cytokinesis
G1 phase
1st phase of Interphase
- cell grows larger
- carries out cellular functions
Synthesis (S) phase
2nd phase of Interphase
- DNA is replicated
- sister chromatids formed
- organelles increase
G2 phase
3rd phase of Interphase
- cell grows larger
- prepares to divide
Interphase
- DNA is diffused chromatin
- no chromosomes are visible
- cell replicates DNA and organelles to enter mitosis
Mitosis
M phase
- Prophase
- Metaphase
- Anaphase
- Telophase
Prophase
1st stage of Mitosis
- chromatin condenses, DNA replication into 2 identical chromsomes called sister chromatids connected by a centromere
- nuclear envelope breaks down
- spindle fibers appear
Metaphase
2nd stage of mitosis
- nuclear envelope is gone
- centromere of each sister chromatid attaches to spindle fibers
- sister chromatids line up along equator
Anaphase
3rd stage of mitosis
- sister chromatids seperate at centromere to produce individual chromosomes
- chromosomes begin to migrate to the poles
Telophase
4th stage of mitosis
- chromsomes reach poles
- spindle fibers disappear
- nuclear envelope and nuclei begin to reform
Cytokinesis
M Phase
- two daughter cells are formed
- each daughter cell enters interphase
Genes
a specfic sequence of DNA which codes for one specific polypeptide
- 30,000 genes in each human cell
Transcription
1st step of protein synthesis
- RNA synthesis: genretes mRNA from one strand of DNA template
1. initiation
2. elongation
3. termination - in nucleus
- end product: mRNA
Translation
2nd step of protein synthesis
- Protein synthesis: process of reading an mRNA message from the gene to make a protein
- end product: protein
- in cytoplasm on ribosomes away from DNA
Genetic code
Codons: 3 base squences along mRNA which code for specific amino acids
Extracellular materials
- Body fluids (plasma, CBS fluid)
- cellular sectrions (gastric fluids, mucus)
- extracellular matrix
