Bio exam 4

Question 1

Mendel’s Hyhybridization experiment

Answer 1

demonstrated that the appearance of different characters in heredity followed specific laws which could be determined by counting types of offspring produced from sets of crosses

Question 2

Mendel’s 4-part model (first part)

Answer 2

Alternative versions of genes (alleles) account for variations in inherited characters.

Question 3

Mendel’s 4-part model (2nd part)

Answer 3

For each character, an organism inherits two (or more) alleles, one from each parent

Question 4

Mendel’s 4-part model (3rd part)

Answer 4

If the two alleles at a locus differ, then the dominant allele determines the organism’s appearance and the recessive allele has no noticeable effect.

Question 5

Mendel’s 4-part model (4th part)

Answer 5

The two alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes

Question 6

Law of segregation

Answer 6

The different alleles for a single trait will be distributed randomly, they will have an equal percentage of appearing in any gamete

Question 7

Complete dominance

Answer 7

occurs when phenotypes of the heterozygote and dominant homozygote are identical

Question 8

Incomplete dominance

Answer 8

the phenotype of F1 hybrids is somewhere between the phenotypes of the two parental varieties

Question 9

Codominance

Answer 9

two dominant alleles affect the phenotype in separate, distinguishable ways

Question 10

Pleiotropy

Answer 10

the phenomenon of a single gene affecting multiple traits

Question 11

Epistasis

Answer 11

a circumstance where the expression of one gene is modified (e.g., masked, inhibited or suppressed) by the expression of one or more other genes

Question 12

Hardy-Weinberg Equilibrium

Answer 12

genotype frequencies in a population remain constant between generations in the absence of disturbance by outside factors

Question 13

Morgan’s fruit fly experiment

Answer 13

Mated male white eyes (mutant) with female red eyes
– F1 generation all had red eyes
– F2 generation showed 3:1 red:white
–only males had white eyes

Question 14

What did Morgan’s fruit fly experiment figure out?

Answer 14

the genetic factor controlling eye color in the flies was on the same chromosome that determined sex

Question 15

Genetic linkage

Answer 15

Genes located on the same chromosome that tend to be inherited together

Question 16

Sex linkage

Answer 16

applies to genes that are located on the sex chromosomes. Their expression and inheritance patterns differ between males and females.

Question 17

Linkage map

Answer 17

is a genetic map of a chromosome based on recombination frequencies

Question 18

Genomic imprinting

Answer 18

the process by which only one copy of a gene in an individual (either from their mother or their father) is expressed, while the other copy is suppressed.

Question 19

How purines and pyrimidine manage the shape of the phosphate backbone

Answer 19

Two purines (T/C): too wide
Two pyrimidines (A/G): too narrow
Purine + pyrimidine: width consistent with X-ray data

Question 20

What are the mechanisms, enzymes, and reactants involved in DNA replication

Answer 20

Replication fork
Helicase
Single-strand binding proteins
Topoisomerase
DNA polymerases
RNA primer
Primase
DNA polymerases

Question 21

Replication Fork

Answer 21

Y-shaped region where new strands are elongating

Question 22

Helicase

Answer 22

unzips the DNA at the replication fork

Question 23

Topoisomerase

Answer 23

Goes before helicase and prevents the double helix from getting too tightly bound, prevents breakage

Question 24

Single-strand binding proteins

Answer 24

Bind to and stabilize single-stranded DNA and separate single DNA strands

Question 25

Primase

Answer 25

starting line creates RNA primers

Question 26

DNA polymerase

Answer 26

replicates DNA

Question 27

Okazaki Fragments

Answer 27

short sections of DNA formed at the time of discontinuous synthesis of the lagging strand during replication of DNA

Question 28

Ligase

Answer 28

Finds gaps between Okazaki fragments & puts them together

Question 29

Nuclease

Answer 29

Cuts out bad sections and signals polymerase to fix it

Question 30

Telomere

Answer 30

attaches to the end of the sequence and protects it (keeps it from getting degraded

Question 31

Steps of Transcription and Translation

Answer 31

Initiation- enzyme RNA polymerase binds to a region of a gene called the promoter.
Elongation- addition of nucleotides to the mRNA strand
Termination- ending of transcription, and occurs when RNA polymerase crosses a stop (termination) sequence in the gene.

Question 32

What is the difference between transcription and translation?

Answer 32

Transcription is the process of transforming DNA into mRNA. Translation is the process of going from mRNA to a polypeptide or a protein.

Question 33

Transcription in Prokaryotes

Answer 33

Prokaryotes- the process in which messenger RNA transcripts of genetic material in prokaryotes are produced, to be translated for the production of proteins

Question 34

Transcription in Eukaryotes

Answer 34

Eukaryotes- carried out in the nucleus of the cell and proceeds in three sequential stages: initiation, elongation, and termination

Question 35

Translation in Prokaryotes

Answer 35

Prokaryotes- translation occurs in the cytosol, where the large and small subunits of the ribosome bind to the mRNA

Question 36

Translation in Eukaryotes

Answer 36

Eukaryotes- the biological process by which messenger RNA is translated into proteins in eukaryotes

Question 37

What are the different types of mutations and how do they happen?

Answer 37

Silent mutation- a change in a nucleotide pair may transform one codon into another that is translated into the same amino acid.

Missense mutation- substitutions that change one amino acid to another one

Nonsense mutation- A point mutation can also change a codon for an amino acid into a stop codon

Frameshift mutation- the number of nucleotides inserted or deleted is not a multiple of three

Question 38

Inducible Operons

Answer 38

one whose expression increases quantitatively in response to an enhancer, an inducer, or a positive regulator

Question 39

Repressible Operons

Answer 39

the other type of operons in prokaryotes, which turn off with the binding of the effector molecule called the co-repressor to the repressor region of the operon