7 GENES AND PROTEINS

Question 1

a large molecule that is consists of one or more polypeptide chain

Answer 1

Protein

Question 2

a series of amino acids that are joined together by a polypeptide bond

Answer 2

polypeptide

Question 3

Enzyme
is a ____

Answer 3

protein

Question 4

are substances that catalyzes or speed up the rate of a chemical reaction

Answer 4

Enzymes

Question 5

These enzymes are ____ in their action

Answer 5

specific

Question 6

Enzymes’ specificity can be attributed to the ____

Answer 6

proteins
composing them

Question 7

properties of enzymes largely depend on their ____

Answer 7

amino acid sequence

Question 8

components of amino acid

Answer 8

amino group
hydrogen
carboxyl group
r-group

Question 9

in an amino acid structure which determines the type of amino acid

Answer 9

R
the side chain

Question 10

Therefore, for the proper functioning of enzyme, it must be of the ____ and is
assembled in the ____. If alteration in the sequence of amino acid occurs, there will be
serious consequences on the phenotype of the individual.

Answer 10

right kind
right order

not all amino acid substitution leads to a disease

Question 11

Relationship between genes and enzymes was first suggested by ____ , an English physician, in 1902

Answer 11

Archibald Garrod

Question 12

The concept was developed as a result of Garrod’s study on a disease called ____

Answer 12

alkaptonuria

Question 13

a recessive trait that causes arthritis

Answer 13

Alkaptonuria

Question 14

2 symptoms of alkaptonuria

Answer 14

• urine of the affected person turns black upon exposure to the air
• serious physical and mental
  retardation (mean IQ – 65)

Question 15

Alkaptonurics cannot metabolize ____ because they lack the enzyme ____

Answer 15

homogentisic acid
homogentisic acid oxidase

homogentisic acid accumulates due to a block in the metabolic pathway

Question 16

In 1941, Beadle and Tatum formulated the ____

Answer 16

One Gene-One Enzyme Hypothesis.

Question 17

One Gene-One Enzyme Hypothesis states that:
a.
b.

Answer 17

(a) every gene controlled a particular enzyme and
(b) the final product of the metabolic process is affected by stepwise succession of enzymes

Question 18

DNA is the one controlling the synthesis of protein through the ____

Answer 18

RNA

Question 19

shows the flow of information in the biological systems

Answer 19

central dogma of molecular biology

Question 20

the informations that are encoded in the DNA are transferred into the RNA in the process
of ____

Answer 20

transcription

Question 21

process that the DNA is
produced from the RNA

which happens to?

Answer 21

reverse transcription

bacteria

Question 22

the informations that are coded in the RNA will be translated
into proteins in the process of ____

Answer 22

translation

Question 23

refers to the transfer of genetic
information from the nucleotide sequence of the DNA
to the nucleotide sequence of the RNA

Answer 23

Transcription

Question 24

2 Steps involved in the transcription

Answer 24

1. Uncoupling of the double stranded DNA molecule.
2. Synthesis of RNA along one DNA strand (catalyst: RNA polymerase)

Question 25

In transcription, the sequence of deoxyribonucleotide in a single DNA strand determines the sequence of ribonucleotides in a newly synthesized RNA. Once the RNA is synthesized, it will move from the ____

Answer 25

nucleus to cytoplasm.

Question 26

Types of ribonucleic acid (RNA):

Answer 26

1. Messenger RNA or mRNA 2. Transfer RNA or tRNA 3. Ribosomal RNA or rRNA

Question 27

carry the instruction for protein synthesis from the DNA (nucleus) to the ribosomes (cytoplasm)

Answer 27

Messenger RNA or mRNA

Question 28

brings the activated amino acids to the mRNA. At least one ____ is specific for each of the 20 amino acids

Answer 28

Transfer RNA or tRNA

Question 29

incorporated in the ribosomes

Answer 29

Ribosomal RNA or rRNA

Question 30

4 features of transcription

Answer 30

a. Involve only certain regions of DNA b. Transcription is the major point of control of gene expression c. RNA synthesis occurs in a 5' to 3' direction d. Transcription consists of three events: initiation, elongation, and termination

Question 31

DNA sequences that code for RNA (mRNA, tRNA, rRNA)

Answer 31

Coding regions

Question 32

do not code for a gene product

Answer 32

Noncoding regions

Question 33

refers to the synthesis of a polypeptide chain using the genetic instructions from the mRNA

Answer 33

Translation

Question 34

7 Steps involved in translation:

Answer 34

a. DNA is transcribed to mRNA in the process of transcription. b. The mRNA moves to the cytoplasm and becomes associated with ribosomes. c. Different RNA’s in the cytoplasm pick up the amino acid and bring them in the ribosome as they move along the mRNA. d. tRNA couples briefly with the mRNA (complementary to RNA bases) in the ribosomes. e. Ribosomes move along the mRNA, adding amino acids to the polypeptide chain. f. As each tRNA donates its amino acid to the growing polypeptide chain, it uncouples from the mRNA. It then moves away from the cytoplasm to pick up more amino acids. g. Once the tRNA completed a peptide chain, it will be release from the ribosomes.

Question 35

Stages of transcription

Answer 35

initiation, elongation, and termination

Question 36

RNA polymerase binds to a sequence of DNA called the ____ found near the beginning of a gene

Answer 36

Initiation promoter

Question 37

# Initiation Each gene (or group of co-transcribed genes, in bacteria) ____

Answer 37

has its own promoter

Question 38

# Initiation Once bound, ____ separates the DNA strands, providing the single-stranded template needed for transcription

Answer 38

RNA polymerase

Question 39

One strand of DNA, the template strand, acts as a template for RNA polymerase. As it "reads" this template one base at a time, the ____ builds an RNA molecule out of complementary nucleotides, making a chain that grows from ____

Answer 39

Elongation polymerase 5' to 3'

Question 40

# Elongation RNA transcript carries the same information as the ____ of DNA, but it contains the base uracil (U) instead of thymine (T)

Answer 40

non-template (coding) strand

Question 41

Sequences called ____ signal that the RNA transcript is complete in the process of ____

Answer 41

terminators Termination

Question 42

very important in decoding the DNA and RNA sequences into amino acids, the building blocks of proteins

Answer 42

Genetic code

Question 43

a collection of base triplets of DNA and RNA carrying the genetic information.

Answer 43

Genetic code

Question 44

There are ____ kinds of amino acids in a protein molecule

Answer 44

20

Question 45

For one DNA, there are ____ kinds of nucleotides

Answer 45

4

Question 46

Why use triplet code of nucleotide?

Answer 46

* One nucleotide for one amino acid = not possible. * Doublet code (2 nucleotides for every one amino acid = not possible for there will be a shortage of 4 codons). * Triplet code (3 nucleotides for one amino acid so there will be an excess of 44 codons)

Question 47

Decoding of mRNAs is being done by reading the nucleotides in group of three, called ____

Answer 47

codon

Question 48

4 important features of codon

Answer 48

a) They specify an amino acid. b) Termination or stop codons mark the end of protein synthesis. c) The codon AUG, which codes for methionine, marks the beginning of protein synthesis d) The mRNA codons are read from 5' to 3' direction. They specify the order of amino acids from the N-terminus to C-terminus

Question 49

5 Features of Genetic Code

Answer 49

1. Genetic Code is triplet 2. Genetic Code is degenerate/redundant/repetitious 3. Genetic Code is non-overlapping 4. Genetic Code is universal 5. There are three nonsense codons

Question 50

Codons for same amino acid usually differ in third position only

Answer 50

Third Base Degeneracy Wobble Hypothesis

Question 51

Evidences that the code is non-overlapping:

Answer 51

Substitution of one nucleotide in a base sequence would only change one amino acid in the protein ## Footnote For instance, in sickle cell anemia, the hemoglobin of the affected person differs from the Hb of the normal person only in one amino acid indicating that a single mutation can result in an alteration of single amino acid.

Question 52

terminator or non-sense codons since they terminate the amino acid chain in the synthesis protein.

Answer 52

UAG, UAA, and UGA