BIO 311C Concept Map
Cell Components
Phospholipid Bilayer
Membrane made up of two fatty acid tails and a hydrophilic head
Fatty acids
Triglycerides
Saturated
Unsaturated
Oils, kinks
Present in plants
Lipids
Glycerol
Mitochondria
Supplies and produces energy for cellular processes
Cell Wall
Protective wall made of cellulose of chitin
Cytoplasm
Place where cell components stay
Vacuole
Contains liquids in cell, two types
Central vacuole
Food vacuole
Nucleus
Contains all genetic information of a cell
Ribosomes
Synthesizes proteins, made of RNA and proteins
Can be free or bound
Proteins
Endoplasmic Reticulum
Synthesizes protein in rough ER
Synthesizes lipids in smooth ER
Golgi Apparatus
Gives instructions to proteins and transports them
DNA Replication
Enzymes involved with DNA
Helicase
Unwinds double helix at replication forks
Primase
Creates RNA primer and attaches on at 5' end of leading strand and multiple on lagging strand
DNA Polymerase III
Synthesizes new DNA strands
DNA Polymerase I
Removes RNA primers and replaces with DNA
Ligase
Connects DNA
Topoisomerase
Relieves strain on DNA strands
DNA Synthesis
Leading Strand
Synthesizes in direction towards replication fork
Lagging strand
Synthesizes in direction away from fork
Replication fork
Where the DNA begins to separate
Origin of Replication
Point in DNA where replication begins
Cell Division
Cell communication
Cells signals one another to tell other cells to begin replication, starting at the phospholipid bilayer
Signal molecules are attached to the phospholipid bilayer and cellular processes begin with the attachment to a receptor molecule
DNA structure
Semi-conservative
Messeleson and Stahl
Strands separated and template synthesizes new complementary strand
Bases
Adenine
Thymine
Guanine
Cytosine
Steps of Replication
Initiation
Begins at ORI, helicase unwinds DNA. Topoisomerase releases tension. RNA primers are created
Elongation
Primer starts making leading strand and uses the existing strand as a template strand. DNA Pol III puts on new bases and lagging strand is synthesized in okazaki fragments. DNA ligase attaches these fragments together
Termination
Gene Regulation
DNA Packaging
Histone core is a protein that binds the DNA
H1, H2A, H2B, H3, H4
H1 is not a part of the core
Nucleosomes formed when DNA wraps around histone twice
Nucleosomes strung together
Interactions between nucleosomes cause thin fiber to coil or fold into thicker fiber
Tight helical fiber needs help of H1
DNA packaged with proteins into chromatin
Prokaryotes
Operons are present
Multiple genes controlled by same promoter
Operator is not in Eukaryotes
Lac Operon
Required for transport and metabolism of lactose
Lac Z forms mRNA
Lac Y takes in lactose
Lac A adds acidicyl group to lactoes
Lac I is lac repressor
Operon off
Lactose absent, repressor on, operon off
Operon on
Lactose present, repressor inactive, operon on
cAMP levels
Lactose present, glucose absent means high cAMP levels and activated CAP
Lactose and glucose present means low cAMP levels and CAP is inactivated
Tryptophan
Amino acid
Negative regulator because binds to repressor
Tryptophan absent, repressor inactivated, operon on
Tryptophan present, repressor active, operon off
Transcription factors
General factors leads to basal level transcription
Repressor binds to enhancer and prevents RNA Pol II to bind
Proximal control elements are close to promoter
Allows RNA Pol II to bind
Transcription factors bind to proximal elements and transcription is low
Specific transcription lead to increased expression
Activators bind to enhancer and bends sequence
Distal control elements are enhancers that are located upstream/downstream of a gene
Cell Signaling
Stages of cell signaling
Reception: Signal molecule binds to receptor protein located at cell's surface
Transduction: Receptor protein changes when signal molecule binds to it. Signal conveyed to form that can bring cellular response. Signal transduction pathway
Cellular response: Transduced signal triggers response
Types of cell signaling
Local
Paracrine
Direct signaling
Synaptic
Neurotransmitters released and diffuses across synapse, stimulating target cell
Signal Molecules
Hydrophobic
Receptor in cell cytoplasm
Receptor in cell nucleus
Hydrophilic
Receptor on/in plasma membrane
Membrane Receptors
G-protein coupled receptor
Cell surgace transmembrane receptor that works with help of G protein
Tyrosine kinase receptor
Allows transfer of phosphate from ATP to tyrosine kinase regions of dimer
Ion Channel receptor
Membrane bound receptor undergoes conformational change, allows for passage of ions
Gene Expression
Translation
Process in which protein is synthesized
Three Steps
Initiation
Small ribosomal unit binds to mRNA. Initiator tRNA binds with start codon
Large ribosomal unit completes initiation complex. Initiation factors in charge of connection of all translation components.
Elongation Cycle
Codon Recognition
Anticodon of aminoacyl tRNA base pairs with complementary mRNA codon in A site. Binds and proceeds
Peptide bond formation
Translocation
Ribosome transolcates tRNA from A site to P site. Empty tRNA in P site moved to E site to get released.
Transcription
Initiation
RNA Pol binds to promoter, DNA strands unwind, Pol initiates RNA synthesis at start point
Transcription in Eukaryotes
TATA box nucleotide sequence (promoter)
Transcription factors bind to DNA before RNA Pol II binds to it
Other transcription factors bind the DNA along with RNA Pol II, forming transcription initiation complex
Elongation
Polymerase moves downstream, unwinding the DNA and elongating the RNA transcription in 5' to 3' direction
Termination
RNA transcript is realsed and polymerase detaches from the DNA
RNA Modifications
5' Cap and Poly A Tail
5' cap and Poly A tail are added to the two ends of pre-mRNA molecule in otder to facilitate the export of mature RNA from the nucleus, protect the mRNA from degrading, and help ribosomes attach to the 5' end of the mRNA when it is in the cytoplasm
RNA splicing
Introns are cut out and exons are spliced together
Lysosome
Breaks down molecules and recycles them
Endocytosis, three types
Receptor mediated
Phagocytosis
Pinocytosis
Photosynthesis
"Synthesis"
Cellular Respiration
Termination
A ribosome reaches the stop codon and the A site accepts a release factor
Release factor promotes hydrolysis of the bond between tRNA in P site and the last amino acid.
Ribosomal subunits and other parts dissociate