7.1 From Gene to Protein

Question 1

importance of genes

Answer 1

Archibald Garrod, in 1896, began studying
alkaptonuria which is a condition where a
person’s urine turns black on contact with air.

He found that people with alkaptonuria excrete a
particular chemical in their urine.

He hypothesized that people with this disorder
were not able to break down this chemical

Later research proved that people with
alkaptonuria have a mutated gene that codes for
a defective enzyme that can no longer break
down the amino acid tyrosine

Question 2

one gene-one polypeptide hypothesis

Answer 2

Each gene codes for the synthesis of one
polypeptide

Different polypeptides can be combined to
form more complex proteins

Can form hormones, enzymes, antibodies etc.

Question 3

central dogma

Answer 3

the fundamental
principle of molecular genetics, which
states that genetic information flows
from DNA to RNA to Proteins

Includes Transcription, Translation,
and Folding

Question 4

from DNA to RNA

Answer 4

Transcription – information in DNA is copied into RNA

RNA can exit the nucleus and enter the cytosol

RNA acts as a copy of the instructions contained in DNA that can be transported outside of the nucleus

RNA can then be used to build proteins

Question 5

translation

Answer 5

information contained within RNA is used to build proteins

RNA contains instructions coding for a specific
amino acid sequence

Involves the use of Ribosomes

Question 6

folding

Answer 6

changing shape of an amino acid chain into a functioning protein

Amino acid chains must fold properly in order
to become functioning proteins

Question 7

RNA

Answer 7

Single Stranded

Adenine pairs with Uracil (A-U not A-T)

Contains Ribose sugar instead of
deoxyribose sugar in DNA

Question 8

3 major types of RNA

Answer 8

Messenger RNA (mRNA), Transfer RNA
(tRNA) and Ribosomal RNA (rRNA)

Question 9

Messenger RNA (mRNA)

Answer 9

translated by ribosomes into a protein

-Used to move the information from DNA to the ribosome where it can be
translated

Varies in length depending on the length of the gene being copied

Question 10

transfer RNA (tRNA)

Answer 10

a carrier molecule that
binds to a specific
amino acid and adds
the amino acid to the
growing polypeptide
chain

Transfers amino acids to ribosomes to help build proteins

Question 11

ribosomal RNA (rRna)

Answer 11

RNA molecules used
with proteins to make up ribosomes

Allow mRNA and tRNA to bind to ribosome

Major component of ribosomes

Question 12

transcription

Answer 12

RNA Polymerase – enzyme that reads DNA and creates a complimentary strand of RNA

RNA is created 5’ to 3’

DNA strand is called the Template Strand

Initial RNA strand has to be modified before it
can become mRNA and is called pre-mRNA or
Precursor mRNA

Question 13

RNA Polymerase

Answer 13

enzyme that reads DNA and
creates a complimentary strand of RNA

Question 14

genetic code

Answer 14

specific coding relationship
between bases and the amino acids they code
for

Question 15

DNA alphabet consists of:

Answer 15

ATCG

Question 16

RNA alphabet consists of:

Answer 16

AUCG

Question 17

codon

Answer 17

three base pairs that code for an
individual amino acid

Question 18

3’ to 5’

Answer 18

DNA

Question 19

5’ to 3’

Answer 19

RNA

Question 20

start codon (AUG)

Answer 20

used to initiate translation
(methionine)

Question 21

stop codon

Answer 21

used to stop translation (UAA,UAG or
UGA)

Question 22

universality of genetic code

Answer 22

The same codons specify the same
amino acids in all living things (there
are a few exceptions)

This demonstrates the fact that DNA
evolved early in our evolution and
remained relatively unchanged
throughout our history

Question 23

one gene-one enzyme hypothesis

Answer 23

proposes each gene is unique and codes for the synthesis of a single enzyme

Question 24

one gene-one polypeptide hypothesis

Answer 24

proposes that each gene is unique and codes for the synthesis of a single polypeptide

Question 25

central dogma

Answer 25

the fundamental principle of molecular genetics, which states that genetic information flows from DNA to RNA to proteins

Question 26

transcription

Answer 26

mechanism by which the info coded in nucleic acids of DNA is copied into the nucleic acids of RNA; something rewritten in the same language

Question 27

translation

Answer 27

mechanism by which the info coded in the nucleic acids of RNA is copied into the amino acids of proteins

Question 28

messenger RNA

Answer 28

the end product of the transcription of a gene; mRNA is translated by ribosomes into a protein

Question 29

transfer RNA

Answer 29

a carrier molecules that binds to a specific amino acid molecule and adds the amino acid to the growing polypeptide chain

Question 30

ribosomal RNA

Answer 30

an RNA molecule within the ribosome that bonds the correct amino acid to the polypeptide chain

Question 31

RNA polymerase

Answer 31

an enzyme that reads a DNA strand and creates a complementary strand of RNA

Question 32

template strand

Answer 32

the DNA strand that is copied into an mRNA molecule during gene transcription

Question 33

precursor mRNA

Answer 33

the initial RNA transcription product

Question 34

genetic code

Answer 34

the specific coding relationship between bases and the amino acids they specify; the genetic code can be expressed in terms of either DNA or RNA bases

Question 35

start codon (initiator codon)

Answer 35

codon that signals the start of a polypeptide chain and initiates translation

Question 36

stop codon

Answer 36

a codon that signals the end of a polypeptide chain and causes the ribosome to terminate translation