Ch. 2 Protein Synthesis

Front 1

genetic code

Back 1

code that is universal among all animal species
contained within the DNA are the codes for the synthesis of all the proteins in out cells

Front 2

cytoplasm

Back 2

Protein synthesis takes place in the _______.

Front 3

Messenger RNA

Back 3

molecule that carries genetic information from the nucleus to cytoplasm
contains the code for the amino acid sequence of a protein

Front 4

Protein synthesis

Back 4

1. DNA is transcribed according to the genetic code to form a complementary mRNA in the nucleus
2. mRNA moves from the nucleus to the cytoplasm
3. mRNA is translated by ribosomes t for the correct A.A. sequence of the protein in the cytoplasm

Front 5

gene

Back 5

portions of DNA that code for a particular protein.

Front 6

Triplets

Back 6

3-base sequence that code for an A.A. sequence.

Front 7

Codon

Back 7

a DNA triplet is complemtary to a 3-base sequence in mRNA that codes for the same A.A. is called a ______.

Front 8

Transcription

Back 8

process in which RNA is synthesized using info in DNA, and it occurs in nucleus.
mRNA
rRNA
tRNA

Front 9

Transcription
Step # 1

Back 9

uncoiling of DNA & its separation into 2 strands at the site where transcription is occuring.

What step of transcription?

Front 10

Transcription
Step # 2

Back 10

1 of the strands of DNA contains the gene and function as template for the sythesis of mRNA. Section w/the DNA & gene is promoter sequence (where RNA polymerase can bind)

What step of transcription?

Front 11

Transcription
Step # 3

Back 11

RNA polymerase binds to the promoter sequence, and initiates that sep. of DNA in two strands. Free RNA nucleotide aligns and is added to new RNA strand. RNA synthesis begins.


What step of transcription?

Front 12

Transcription
Step # 4

Back 12

mRNA undergoes post-transcription processing in nucleus before the final mRNA product moves through the nuclear pores and enter the cytoplasm.
What step of transcription?

Front 13

Transcription
Step # 5

Back 13

introns that don't code for the A.A. sequence of proteins must be removed before leaving nucleus.

What step of transcription?

Front 14

Transcription
Step # 6

Back 14

Exons are the remaining coding segments from introns. They group together.

What step of transcription?

Front 15

Transcription
Step # 7

Back 15

CAP (chemical) is added to end of strand to protects mRNA from degradation in cytoplasm.

What step of transcription?

Front 16

Transcription
Step # 8

Back 16

mRNA enter cytoplasm, and translation of mRNA can occur

Front 17

translation

Back 17

The process of peptide formation from the instructions carried by an mRNA strand.

Front 18

tRNA

Back 18

carries the appropriate amino acid to the ribosome based on the interactions with the mRNA codon.

shaped like a cloverleaf

Front 19

tRNA

Back 19

Hydrogen bonding btwn complementary base pairs is responsible for the cloverleaf structure

Binds a specific A.A. on one end, and it hasa base sequence called an anticodon on the other end that recognizes the complementary mRNA codon.

Front 20

initiation

Back 20

first step in translation

Front 21

initiation of translation

Back 21

initiation factors bind to the CAP region of a mRNA molecule and to the small ribosomal subunit, triggering the binging of the small ribosomal subunit of the mRNA. A tRNA with the anticodon complementary to the initiation codon of mRNA binds to the mRNA by the law of complementary base pairing. The large ribosomal subunit binds such that the first tRNA is located in the Psite of the ribosome, and the initiation factors are released

Front 22

translation

Back 22

a process by which an encyme in the ribosome catalyzes the formation of a peptide bond btwn the 2 A.A.s. The 1st A.A., whish is always Methionine, is released from the tRNA molecule, and the free tRNA (tRNA without its A.A.) leaves the Psite on the ribome. The ribosome then moves down the mRNA 3 bases (one codon), placing the second tRNA in the P site on the ribosome. The next charged tRNA enters the A site, bringing in the 3rd A.A. to be added to the polypeptide. This process continues until a termination codon is reached of the mRNA. At that point, the polypeptide is released, and the ribosome and mRNA disoiciate. More than one ribosome traslates a given mRNA molecule at the same time, forming what is called a polyribosome.

Front 23

anticodon

Back 23

complementary codon to mRNA codon

Front 24

nucleus
cytosol
plasma membrane
organelles
extracellular fluid

Back 24

Where do synthesized proteins go?

Front 25

leader sequence

Back 25

initial sequence of A.A. that is present in a newly synthesized polypeptide chain and functions in directing fate of final protein.

Front 26

Protein synthesis in E.R.

Back 26

Starts in cytosol
leader sequence & ribosome bind to protein on E.R. (signal recognition proteins)
A polypeptide chain passes through rough E.R. to lumen of smooth E.R., and then eventually to Golgi apparatus.

Front 27

Regulation of transcription

Back 27

mRNA binds to proteins in cytoplasm that render in inactive until an appropriate chemical signal is received
other mRNA is degraded by enzymes in cytosol
m RNA is needed in protein synthesis, the rate of _______ affects the amount of protein in cell. ________ can be turned on or off depending if cells require more or less proteins.

Front 28

Regulation of transcription

Back 28

usually occurs when RNA polymerase binds to promoter sequence on DNA. Certain molecules either enhance or decrease the ability of RNA polymerase to bind to promoter sequence.

Front 29

Regulation of Translation

Back 29

occurs during initiation (first step)
needs to be at least 11 proteins, including initiation factors
Proteins can be rendered active or inactive (on or off)

Front 30

Proteases

Back 30

An enzyme that breaks down proteins into peptides and amino acids.

Front 31

Ubiquitin

Back 31

To prevent the indiscriminant destruction of cytosolic proteins, those proteins to be destroyed are tagged with a polypeptide called _________.

functions like leader sequence - it tells protein to go to protesome.

Front 32

Protesome

Back 32

a protein complex which contains proteases that degrade the protein into small peptide fragments

Front 33

Translation

Back 33

using ribosomes and tRNA to "read" mRNA base sequence and connect A.A. together to form the desired polypeptide.