Theme 1: Proteins
2.5.1 Proteins are composed of amino acids.
• Some proteins act as enzymes and others as structural components
necessary for cell shape and movement
•
• The R group/side chain differs between amino acids
◦ Example: Glycine's side chain is H
◦ Example: Alanine's side chain is CH3
• Cellular proteins are made of 20 amino acids which can be classified
based on the chemical properKes of their side chains
• Sequence of amino acids determines how it folds into its 3-D shape
1.3.1 Nucleic acids store and transmit informa8on needed
for growth, func8on and reproduc8on.
• InformaKon encoded in DNA directs the formaKon of proteins
◦ ExisKng proteins create a copy of the DNA's informaKon in the
form of RNA in a process known as transcrip8on (synthesis of RNA
from a DNA template)
◦ Specialized molecular structures within the cell then "read" the
RNA molecule to determine what amino acids to use to create a
protein in a process known as transla8on
• Central Dogma: The pathway from DNA to RNA (specifically to a form of
RNA called messenger RNA, or mRNA) to protein
◦ Describes the basic flow of informaKon in a cell
◦ First proposed by Crick
• Gene- The DNA sequence that corresponds to a specific protein product
• During DNA replicaKon, each strand of the double helix serves as a
template for a new strand
3.1.3 Gene8c informa8on flows from DNA to RNA to
protein.
, • In specifying the amino acid sequence of proteins, DNA acts through
RNA (a linear polymer)
• ExcepKons to the central dogma:
◦ Transfer of geneKc informaKon from RNA to DNA (as in HIV)
◦ Transfer of geneKc informaKon from RNA to RNA (as in the
replicaKon of the geneKc material of the influenza virus)
◦ Transfer of geneKc informaKon from protein to protein (as in the
case of prions)
• Transcrip8on- GeneKc informaKon in a molecule of DNA is used as a
template to generate a molecule of RNA; First step in gene expression
• Transla8on- A molecule of RNA is used as a code for the sequence of
amino acids in a protein
• Genes are expressed at certain Kmes and at certain places
• Prokaryotes- TranscripKon and translaKon occur in the cytoplasm
• Eukaryotes- TranscripKon occurs in the nucleus and translaKon occurs in
the cytoplasm; This separaKon allows for addiKonal levels of gene
regulaKon that aren't possible in prokaryoKc cells (though both types of
cells have such similar processes for gene expression that it must have
evolved early in evoluKonary history)
5.4.2 The nucleus houses the genome and is the site of RNA
synthesis.
• Nuclear Envelope- Defines the boundary of the nucleus; Consists of an
inner and outer membrane; The two membranes are conKnuous at
protein openings called nuclear pores which act as gateways to allow
molecules to move into and out of the nucleus
• Transfer of informaKon encoded by DNA depends on the movement of
RNA molecules out of the nucleus
• Control of how and when this informaKon is expressed depends on the
movement of proteins into the nucleus
5.4.3 The endoplasmic re8culum is involved in protein and
lipid synthesis.
• Outer membrane of the nucleus is physically conKnuous with the ER
2.5.1 Proteins are composed of amino acids.
• Some proteins act as enzymes and others as structural components
necessary for cell shape and movement
•
• The R group/side chain differs between amino acids
◦ Example: Glycine's side chain is H
◦ Example: Alanine's side chain is CH3
• Cellular proteins are made of 20 amino acids which can be classified
based on the chemical properKes of their side chains
• Sequence of amino acids determines how it folds into its 3-D shape
1.3.1 Nucleic acids store and transmit informa8on needed
for growth, func8on and reproduc8on.
• InformaKon encoded in DNA directs the formaKon of proteins
◦ ExisKng proteins create a copy of the DNA's informaKon in the
form of RNA in a process known as transcrip8on (synthesis of RNA
from a DNA template)
◦ Specialized molecular structures within the cell then "read" the
RNA molecule to determine what amino acids to use to create a
protein in a process known as transla8on
• Central Dogma: The pathway from DNA to RNA (specifically to a form of
RNA called messenger RNA, or mRNA) to protein
◦ Describes the basic flow of informaKon in a cell
◦ First proposed by Crick
• Gene- The DNA sequence that corresponds to a specific protein product
• During DNA replicaKon, each strand of the double helix serves as a
template for a new strand
3.1.3 Gene8c informa8on flows from DNA to RNA to
protein.
, • In specifying the amino acid sequence of proteins, DNA acts through
RNA (a linear polymer)
• ExcepKons to the central dogma:
◦ Transfer of geneKc informaKon from RNA to DNA (as in HIV)
◦ Transfer of geneKc informaKon from RNA to RNA (as in the
replicaKon of the geneKc material of the influenza virus)
◦ Transfer of geneKc informaKon from protein to protein (as in the
case of prions)
• Transcrip8on- GeneKc informaKon in a molecule of DNA is used as a
template to generate a molecule of RNA; First step in gene expression
• Transla8on- A molecule of RNA is used as a code for the sequence of
amino acids in a protein
• Genes are expressed at certain Kmes and at certain places
• Prokaryotes- TranscripKon and translaKon occur in the cytoplasm
• Eukaryotes- TranscripKon occurs in the nucleus and translaKon occurs in
the cytoplasm; This separaKon allows for addiKonal levels of gene
regulaKon that aren't possible in prokaryoKc cells (though both types of
cells have such similar processes for gene expression that it must have
evolved early in evoluKonary history)
5.4.2 The nucleus houses the genome and is the site of RNA
synthesis.
• Nuclear Envelope- Defines the boundary of the nucleus; Consists of an
inner and outer membrane; The two membranes are conKnuous at
protein openings called nuclear pores which act as gateways to allow
molecules to move into and out of the nucleus
• Transfer of informaKon encoded by DNA depends on the movement of
RNA molecules out of the nucleus
• Control of how and when this informaKon is expressed depends on the
movement of proteins into the nucleus
5.4.3 The endoplasmic re8culum is involved in protein and
lipid synthesis.
• Outer membrane of the nucleus is physically conKnuous with the ER
