Chapter 16

Question 1

how did scientists first establish what genes do?

Answer 1

started out using metabolic pathways?

Question 2

how did scientists use metabolic pathways to figure out what genes do?

Answer 2

they manipulated one step of the metabolic pathway and wherever the next enzyme fails, there will be an accumulation of the previous substrate

Question 3

who studied what genes do?

Answer 3

Beadle and Tatum

Question 4

what experiment did Beadle and Tatum do?

Answer 4

they studied metabolic pathways for arginine synthesis

Question 5

what question did Beadle and Tatum ask?

Answer 5

is there a 1:1 relationship between genes and proteins or does one gene encode all proteins needed for arginine synthesis

Question 6

what were the steps for the genetic screen used by Beadle and Tatum?

Answer 6

1. mutagenize (treat with) a population of cells (with UV or X-rays)
2. grow mutagenized cells on media that included arginine.
3. transfer to media that lacks arginine, look for cells that fail to grow.
4. isolate those cells and study them

Question 7

what does it mean to have cells that grow on arginine plates but do not grow on plates with no arginine?

Answer 7

those cells have mutations in genes that are used for arginine synthesis

Question 8

what was the conclusion for Beadle and Tatum’s experiment?

Answer 8

there is a one to one gene and enzyme relationship.
*not for all synthesis but just some.

Question 9

information in a gene (nucleotides) are converted into what?

Answer 9

amino acids of a protein

Question 10

in Eukaryotes how is information moved from nucleus and into the cytoplasm?

Answer 10

DNA is made in the nucleus
Protein synthesis happens in the cytoplasm
mRNA connects the molecules

Question 11

what are the steps of the central dogma

Answer 11

Genes (DNA; information storage) —- transcription ——-mRNA (information carrier) ——-translation ———– protein (do the work of the cell)

Question 12

how do genotypes relate to phenotypes?

Answer 12

if there is one gene different, the translation will be different making the proteins different, so the animal will appear different

Question 13

true or false:
not all genes encode a protein. Some end at the mRNA step

Answer 13

true

Question 14

how many bases does mRNA need?

Answer 14

three

Question 15

what is a codon?

Answer 15

three bases in mRNA that contain genetic information for amino acid; pair to something on the genetic codon chart

Question 16

what way do the mRNA read?

Answer 16

5’ to 3’

Question 17

what is the start codon?

Answer 17

AUG

Question 18

what are the stop codons?

Answer 18

UAA
UAG
UGA

Question 19

what is the most abundant codon in humans?

Answer 19

GAA
GAG
= Glutamic acid

Question 20

silent definition

Answer 20

change in nucleotide sequence that does not change the amino acid sequence by a codon

Question 21

missense definition

Answer 21

change in nucleotide sequence that changes

Question 22

nonsense definition

Answer 22

change in nucleotide sequence that results in an early stop codon

Question 23

frameshift definition

Answer 23

addition or deletion of a nucleotide

Question 24

steps for using the genetic code

Answer 24

given DNA
1. match to RNA base pairs (A-U, G-C), called transcription
2. match those to the codons in the chart, called translation

Question 25

point mutations definition

Answer 25

single base change to a gene

Question 26

why do point mutations happen?

Answer 26

they caused by uncorrected errors in DNA replication