Gene Expression

Question 1

gene expression

Answer 1

Overall process by which the information encoded in genes is converted into an active product, most commonly a protein. Includes transcription and translation of a gene and in some cases protein activation.

Question 2

loss of function alleles

Answer 2

A mutant allele that does not function at all, or an organism homozygous for such a mutation.

Question 3

one gene, one enzyme hypothesis

Answer 3

The hypothesis that each gene is responsible for making one (and only one) protein, in most cases an enzyme that catalyzes a specific reaction. Many exceptions to this hypothesis are now known.

Question 4

metabolic pathway

Answer 4

An ordered series of chemical reactions that build up or break down a particular molecule. Often, each reaction is catalyzed by a different enzyme.

Question 5

genetic screen

Answer 5

Any of several techniques for identifying individuals with a particular type of mutation. Also called a screen.

Question 6

What do genes do?

Answer 6

They contain the instructions for making proteins

Question 7

messenger RNA

Answer 7

An RNA molecule that carries encoded information, transcribed from DNA, that specifies the amino acid sequence of a polypeptide.

Question 8

RNA polymerase

Answer 8

One of a class of enzymes that catalyze synthesis of RNA from ribonucleotides, using a DNA template. Also called RNA pol.

Question 9

central dogma

Answer 9

The long-accepted hypothesis that information in cells flows in one direction: DNA codes for RNA, which codes for proteins. Exceptions are now known (e.g., retroviruses).

Question 10

Transcription

Answer 10

The process by which RNA is made from a DNA template.

Question 11

Translation

Answer 11

The process by which proteins and peptides are synthesized from messenger RNA.

Question 12

What are some changes to central dogma since its inception?

Answer 12

• sometimes info flows from RNA to DNA

- many genes code for RNA molecules that do not function as mRNA..they are not all translated into proteins

Question 13

reverse transcriptase

Answer 13

An enzyme of retroviruses (RNA viruses) that can synthesize double-stranded DNA from a single-stranded RNA template.

Question 14

genetic code

Answer 14

The set of all 64 codons and the particular amino acids that each specifies.

Question 15

triplet code

Answer 15

A code in which a “word” of three letters encodes one piece of information. The genetic code is a triplet code because a codon is three nucleotides long and encodes one amino acid.

Question 16

codon

Answer 16

A sequence of three nucleotides in DNA or RNA that codes for a certain amino acid or that initiates or terminates protein synthesis.

Question 17

reading frame

Answer 17

The division of a sequence of DNA or RNA into a particular series of three-nucleotide codons. There are three possible reading frames for any sequence.

Question 18

start codon

Answer 18

The AUG triplet in mRNA at which protein synthesis begins; codes for the amino acid methionine.

Question 19

stop codon

Answer 19

One of three mRNA triplets (UAG, UGA, or UAA) that cause termination of protein synthesis. Also called a termination codon.

Question 20

point mutation

Answer 20

A mutation that results in a change in a single nucleotide pair in a DNA molecule.

Question 21

missense mutation

Answer 21

A point mutation (change in a single base pair) that causes a change in the amino acid sequence of a protein.

Question 22

replacement mutations

Answer 22

Same as missense mutation

Question 23

silent mutation

Answer 23

A mutation that does not detectably affect the phenotype of the organism.

Question 24

What are the three categories of mutation?

Answer 24

1) Beneficial
2) Neutral
3) Deleterious-harmful

Question 25

polyploidy

Answer 25

The state of having more than two full sets of chromosomes.

Question 26

aneuploidy

Answer 26

The state of having an abnormal number of copies of a certain chromosome.

Question 27

inversion

Answer 27

A mutation in which a segment of a chromosome breaks from the rest of the chromosome, flips, and rejoins with the opposite orientation as before.

Question 28

translocation

Answer 28

A type of mutation in which a piece of a chromosome moves to a nonhomologous chromosome. The process by which a ribosome moves down a messenger RNA molecule during translation.

Question 29

cancer cells normally contain what types of mutations?

Answer 29

aneupolidy, inversions and translocations