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3/22/16
Cytoskeleton - a system of protein filaments that extend through cytosol
The cytoskeleton helps support the large volume of cytosol inside a cell
Most prominent in eukaryotic cells
However, unlike our static skeleton, the cytoskeleton is dynamic
Cytoskeletal filaments are made of noncovalently-linked subunits
*allows for rapid assembly and disassembly*
Filaments can disassemble and reassemble in different locations in cell
RNAs as Intermediates in the Flow of Genetic Information
Transcription by DNA dependent RNA polymerase
RNA processing - pre RNA RNA
Translation
protein processing
polypeptide protein
RNAs function in RNA processing:
snRNA
snoRNA
RNAs function in translation:
mRNA,
tRNA
rRNA
DNA Transcription (Slide 20)
The ?Central Dogma? - Crick 1958
DNA - RNA - Protein
Proposed that this process could not go backwards
The part of DNA that encodes for a protein (or RNA) is called a gene
GENE: Functional unit of DNA that codes for one or more polypeptide chains or an RNA molecule
Genome is not just genes, there are intervening sequences that don?t code for a protein
DNA Replication
As the genetic information, DNA must be faithfully replicated and passed down to the next generation
The structure of DNA immediately suggested a replication mechanism
A strand of DNA can serve as a template for replication
If you know one strand, you can determine the other
What is the mechanism of replication?
Meselson & Stahl used density centrifugation
biomolecules will float or sink until they reach the point at which their density equals that of the gradient
Nucleic Acids, DNA Structure, and Chromosomes
Nucleotides are the building blocks of nucleic acids
One (NMP), two (NDP), three (NTP) phosphates
5 different bases: A, G, C (DNA and RNA), T (DNA), U (RNA)
2 different sugars: ribose (RNA), deoxyribose (DNA)
Two kinds of 5-carbon sugars
Five kinds of nitrogen containing bases
Nucleic Acids, DNA Structure, and Chromosomes
Nucleotides are the building blocks of nucleic acids
One (NMP), two (NDP), three (NTP) phosphates
5 different bases: A, G, C (DNA and RNA), T (DNA), U (RNA)
2 different sugars: ribose (RNA), deoxyribose (DNA)
Two kinds of 5-carbon sugars
Five kinds of nitrogen containing bases
LIPIDS & MEMBRANE STRUCTURE
Lipids differ from the other macromolecules: not formed by linear polymerization
however, they do have a high molecular weight
they contribute to important cellular structures (membranes)
Protein Function and Enzymes
Most proteins function by binding to other molecules
Antibody - aggregating foreign
Actin - binding to itself
Enzymes
Hexokinase - binding pocket for glucose, then catalyze
Selectivity comes into play based on functional groups
Proteins bind other molecules at the binding site
Unique chemical environment
Not only based on agreeing shape, but also non-covalent bonds
In some cases this binding is very tight; in others it is weak and short lived.
Chemical Components of Cells Part II- Protiens 1.19.16
Proteins are composed of amino acids
General structure of an amino acid where R is one of twenty different side chains
At pH=7, both the carboxyl and amino groups are polarized
In cell, cytosol will always make it ionized
Amino acids are linked together by peptide bonds
R Groups have different chemical properties:
Be able to decide if each R-group is hydrophobic or hydrophilic
Chemical Components of Cells - Part I: Sugars 1/14
Living organisms are chemical systems
Cells contain relatively few elements
The distribution of elements differs dramatically from living organisms to inanimate matter
Mostly carbon, nitrogen, oxygen, and hydrogen
Why do living organisms contain so much hydrogen and oxygen?
Water is the most abundant molecule in the cell
Bio 230: Cell Bio
Intro to Cells: pg 1-26
Properties that define living organisms:
Ability to reproduce on their own
Viruses? Not living organisms but incapable of reproducing on their own
Can grow and develop
Require energy - metabolism
Response to the environment
Maintain homeostasis
Contains genetic information (DNA or RNA)
Composed of cells
Cells are the fundamental unit of life.
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