Protein Synthesis

Front 1

gene

Back 1

a small segment on a chromosome which codes for a unique protein
(contains information on how to make a protein)

Front 2

nucleotide

Back 2

single units that make up nucleic acid
-DNA RNA

Front 3

transciption

Back 3

formation of mRNA from DNA

Front 4

translation

Back 4

formation of a protein from mRNA
-converting a nucleotide sequence into an amino acid sequence

Front 5

template strand

Back 5

where the RNA polymerase binds

Front 6

RNA polymerase

Back 6

enzyme that reads the DNA bases and brings in a complimentary RNA base to bind

Front 7

DNA triplet

Back 7

found on DNA -3 bases that make up to the complimentary base. attaches in threes

Front 8

complimentary base pairing

Back 8

a-u (RNA)
T-a
g-c
c-g

Front 9

messenger RNA (mRNA)

Back 9

the message strand that carries the code for a protein from the DNA into the cytoplasm
-stays as a linear strand

Front 10

ribosomal RNA

Back 10

combines with proteins to make ribosomes

Front 11

transfer RNA

Back 11

cytoplasmic RNA strand folded into cloverleaf binds an amino acid at one end
-shuttles A.A. around

Front 12

codon

Back 12

different combination of mRNA nucleotides
mRNA triplets

Front 13

anticodon

Back 13

tRNA molecules that each have different binding regions at one end
tRNA triplets

Front 14

amino acid

Back 14

added until the end of the mRNA stand is reached in translation

Front 15

peptide bond

Back 15

a small chain of amino acids (less than 1000)

Front 16

ribosome

Back 16

cytoplasm organelle
made of ribosomal RNA and protein
two separate parts that come together in the cytoplasm (can exist as two separate parts) small and large subunits

Front 17

endoplasmic reticulum

Back 17

where the protein from the ribosome will be associated with membrane as it forms

Front 18

Golgi apparatus

Back 18

organelle that modifies, packages and directs proteins to their final destination

Front 19

vesicle

Back 19

carriers of proteins and other material during exocytosis

Front 20

secretory vesicle

Back 20

vesicles for exocytosis

Front 21

lysosomes

Back 21

vesicles filled with digestive enzymes- responsible for break down of ingested substances and also autolysis

Front 22

Name the four DNA bases.

Back 22

Cytosine
Guanine
adenine
thymine

Front 23

Name the four RNA bases

Back 23

cytosine guanine
adenine uracil

Front 24

Explain why DNA is called the “information storage” part of the cell.

Back 24

DNA=series of recipes-> each cell uses which recipe it;ll use for coding proteins
-20diff amino acids, each encoded by DNA by a specific 3-nucleotide sequence on one stand of DNA- gene contains all the triplets needed to code for a specific polypeptide

Front 25

Explain the relationship between a chromosome and a gene.

Back 25

A gene is a small segment on a chromosome which codes for a unique protein

Front 26

Describe the relationship between amino acids and a functional protein.

Back 26

Proteins are made from a linear string of amino acids (primary structure). In order for the protein to be functional, the protein must twist or fold into secondary and tertiary structures, and sometimes joining with other protein subunits (quaternary structure). A protein with the wrong folding pattern is usually nonfunctional.

Front 27

Describe the steps in transcription. Where in the cell does this occur?

Back 27

Transcription occurs in the nucleus. The two DNA strands of the double helix are separated by breaking the
weak hydrogen bonds holding the strands together, exposing the bases and allowing an enzyme called RNA polymerase to copy one of the DNA strands in the region of just the one gene. RNA nucleotides floating in the
nucleoplasm come in and form hydrogen bonds with the exposed bases on the template strand by
complementary base pairing: cytosine nucleotides bond with guanine nucleotides; an adenine nucleotide on the template DNA bonds with a uracil RNA nucleotide, while a thymine nucleotide on the DNA strand bonds with an adenine RNA nucleotides. The RNA polymerase catalyzes bond formation between the newly attached nucleotides, attaching the ribose sugar of one new RNA nucleotide to the phosphate of the adjacent RNA
nucleotide. In this way, RNA polymerase moves along the gene and creates a new strand of RNA nucleotides which are complementary to the DNA template strand. This new strand is similar to the DNA coding strand but is made of RNA nucleotides rather than DNA nucleotides. DNA strand has been transcribed into an RNA
strand that we call messenger RNA.

Front 28

What mRNA segment would be created from a template strand segment of DNA with the following base
sequence?
CGAATTGGCAGCTGC

Back 28

GCUUAACCGUCGACG

Front 29

What is the role of the ribosome in protein synthesis?

Back 29

The ribosome serves as the site of protein assembly; it is where the mRNA strand docks, has binding sites for tRNA, and has enzymes which catalyze the bonding of one amino acid to another to form a peptide chain.

Front 30

Describe the structure of a tRNA molecule and relate it to its function in the cell.

Back 30

The tRNA molecule is a single strand of RNA that is twisted into a structure resembling a cloverleaf. One end of the tRNA molecule has a set of 3 nucleotide bases we call the anticodon. The anticodon bases are
complementary to the bases of an mRNA codon. The other end of the molecule has a binding site specific for one of the 20 different amino acids. tRNA is so-named because it transports, or shuttles, amino acids from the cytoplasm to the ribosome.

Front 31

Describe the process of translation. Where in the cell does this occur?

Back 31

The process of translation occurs in the cytoplasm. First, an mRNA molecule attaches to the small ribosomal subunit. The large ribosomal subunit then comes in and joins the small subunit, forming a functional ribosome. The first (start) codon, a series of 3 nucleotides at one end of the mRNA strand is then “read”; a tRNA molecule with 3 bases (the anticodon) complementary to those of the codon docks at the binding site on the small subunit and brings with it a particular amino acid. A second tRNA anticodon base-pairs with the second mRNA codon, bringing with it a second amino acid. Enzymes of the ribosome catalyze the removal of a water molecule
between the two amino acids, forming a peptide bond. The mRNA strand then shifts through the ribosome by one codon; the third codon is now in position to base-pair with a new complementary tRNA anticodon, and
another amino acid is brought into position and joined to the other two amino acids. In this way, a chain of
amino acids is formed, forming a peptide (a short sequence of amino acids) which can continue to elongate; really long peptides are called proteins. In the process of translation, the mRNA strand - a string of RNA nucleotides- is translated into a string of amino acids.

Front 32

What types of proteins are assembled on free ribosomes?

Back 32

Proteins that work in the cytoplasm are assembled on free ribosomes and released into the cytoplasm;
cytoplasmic enzymes, and those proteins that make up the cytoskeleton are examples.
Proteins that work in the nucleus are assembled on free ribosomes, then directed to the nucleus and transported in through a nuclear pore. Histone proteins are an example of a nuclear protein.

Front 33

What types of proteins are assembled on fixed ribosomes?

Back 33

Fixed ribosomes are those that attach to the endoplasmic reticulum early in the process of translation. This occurs when they are assembling a protein that needs to be either sequestered completely within a vesicle of membrane (example 1: the enzymes of a lysosome, which would eat away the cell if not hidden in membrane; example 2: the hormone insulin, which is carried in a secretory vesicle to the plasma membrane where it will be released from the cell by exocytosis). Another type of protein needing to be associated with membrane as it is assembled is a protein destined to become part of the plasma membrane, either as a peripheral protein or as a transmembrane protein.

Front 34

Describe how a protein destined to become an integral membrane protein is translated, processed, and inserted
in the membrane. What organelles are involved?

Back 34

Like all proteins, translation begins on a free ribosome. Information coded in the first part of the mRNA signals the ribosome to move to the endoplasmic reticulum and dock there. Translation then continues, and the growing chain of amino acids links into the ER membrane; some charged amino acids prefer to face either the watery cytoplasm or the watery interior of the ER, while uncharged amino acids are happy within the
hydrophobic region of the phospholipid bilayer.. The growing protein is thus threaded through the ER membrane, sticking out both sides. The finished protein leaves the ER in vesicle, but remains threaded through the ER membrane rather than completely surrounded by membrane. The vesicle fuses with membrane of the Golgi apparatus, where changes can be made to the protein, and leaves the other side of the Golgi, again
threaded through the membrane of the vesicle. The vesicle is directed to the plasma membrane; as the vesicle
membrane fuses with the plasma membrane, the embedded protein now becomes a transmembrane protein at the surface of the cell.

Front 35

What kind of a molecule is RNA polymerase? How do you think this molecule would be produced and how
would it get into the nucleus?

Back 35

RNA polymerase is an enzyme, and a protein. As a protein active in the nucleus, it would have been assembled on a free ribosome in the cytoplasm and brought into the nucleus through a nuclear pore.