Biology 1 Chapter 15 (Lecture)

Question 1

The reason that linked genes are inherited together is that

Answer 1

They are located on the same chromosome

Question 2

What is the mechanism for the production of genetic recombinants?

Answer 2

Crossing over and independent assortment

Question 3

Males are more often affected by sex-linked traits than females because

Answer 3

Males are hemizygous for the X chromosome

Question 4

A man who carries an X-linked allele will pass it on to

Answer 4

All of his daughters

Question 5

What syndrome afflicts mostly males?

Answer 5

Duchenne Muscular Dystrophy

Question 6

If a chromosome lacks certain genes, what has most likely occurred?

Answer 6

A deletion

Question 7

Of the Human trisomies, the one that generally has the most severe impact on the health of the individual is

Answer 7

Trisomy 21

Question 8

What do all human males inherit from their mother?

Answer 8

An X chromosome and mitochondria DNA

Question 9

What is false about Down’s Syndrome?

Answer 9

It is a sex-linked disorder

Question 10

What is not true of Turner’s Syndrome?

Answer 10

They are genetically XXX

Question 11

What results in male sex organs but may have some female body characteristics present? (They are also sterile and may have subnormal intelligence)

Answer 11

XXY

Question 12

What is not a sex-linked disorder?

Answer 12

Sickle Cell Anemia

Question 13

What kind of chemical bond is found between paired bases of the DNA double helix?

Answer 13

Hydrogen

Question 14

In an analysis of the nucleotide composition of DNA, what is true?

Answer 14

A+C=G+T and G+A=T+C

Question 15

The strands that make up DNA are antiparallel. This means that

Answer 15

The 5’ to 3’ direction of one strand runs counter to the 5’ to 3’ direction of the other strand

Question 16

What is the function of DNA polymerase?

Answer 16

To add nucleotides to the end of a growimng DNA strand

Question 17

Removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3’ end of Okazaki fragments

Answer 17

DNA polymerase I

Question 18

Separates the DNA strands during replication

Answer 18

Helicase

Question 19

Covalently connects segments of DNA

Answer 19

Ligase

Question 20

Synthesizes short segments of RNA

Answer 20

Primase

Question 21

Wild Type

Answer 21

The phenotype for a character most commonly observed in natural populations

Question 22

Mutant Phenotypes

Answer 22

Traits that are alternatives to the wild type.

Because they are due to alleles assumed to have originated as changes or mutations in the wild type allele.

Question 23

Sex-Linked Gene

Answer 23

A gene located on either sex chromosome

Question 24

Fathers pass sex-linked alleles to all of their…

Answer 24

Daughters but none to their sons.

Question 25

Mothers can pass sex-linked alleles to...

Answer 25

Sons and Daughters

Question 26

Far more _____ have sex-linked recessive disorders

Answer 26

Males

Question 27

Male sex-linked recessive disorders

Answer 27

* Color Blindness * Duchenne Muscular Dystrophy * Hemophilia

Question 28

Duchenne Muscular Dystrophy

Answer 28

* 1/3500 males born in US * Progressive weakening of the muscles and loss of coordination * Rarely live past early 20's * Absence of a key muscle protein (dystrophin) and have mapped the gene for this protein to specific locus on the x chromosome

Question 29

Hemophilia

Answer 29

Defined by the absence of one or more of the proteins required for blood clotting * Bleeding is prolonged because firm clot is slow to form * Small cuts are usually ok; but bleeding in the muscles or joints can be painful and can lead to serious damage * Treated as needed with IV injections of the missing proteins.

Question 30

Barr Body

Answer 30

The inactive X in each cell of a female condenses into a compact object. Most of these genes are not expressed. Females are a mosaic of two types of cells: those with active X derived from the father and those with active X derived from the mother.

Question 31

Linked Genes

Answer 31

Genes located on the same chromosome that tend to be inherited together in genetic crosses.

Question 32

Genetic Recombination

Answer 32

Offspring that inherit a phenotype that is different from either parent

Question 33

If there is a 50% frequency of recombination in a heterozygous x homozygous testcross tells us...

Answer 33

That the two genes are located on different chromosomes and are thus unlinked.

Question 34

Crossing Over

Answer 34

Accounts for the recombination of linked genes. In this end portions of two nonsister chromatids trade places each time a crossover occurs.

Question 35

Genetic Map

Answer 35

An ordered list of the genetic loci along a particular chromosome.

Question 36

The farther apart two genes are, the higher the probability that...

Answer 36

A crossover will occur between them and therefore the higher the recombination frequency.

Question 37

Linkage Map

Answer 37

A genetic map based on recombination frequencies

Question 38

Nondisjunction

Answer 38

A mishap in which the members of a pair of homologous chromosomes do not move apart properly during meiosis I or sister chromatids fail to separate during meiosisII. In these cases, one gamete receives 2 of the same type of chromosome and the other receives 0 copies.

Question 39

Aneuploidy

Answer 39

If this aberrant gamete unites with a normal on at fertilization the zygote will have an abnormal number of chromosomes.

Question 40

Alterations of chromosome structure due to chromosome breakage:

Answer 40

* Deletion * Duplication * Inversion * Translocation

Question 41

Deletion

Answer 41

Chromosomal fragment is lost

Question 42

Duplication

Answer 42

When an extra segment is attached to a sister chromatid

Question 43

Inversion

Answer 43

reverses a segment within the chromosome

Question 44

Translocation

Answer 44

Moves a segment from one chromosome to a nonhomologous chromosome

Question 45

Genes located in organelles in the cytoplasm contain small circular DNA molecules

Answer 45

* Mitochondria * Chloroplasts * Plant Plastids

Question 46

Almost all mitochondrial DNA is...

Answer 46

Maternal DNA almost all the mitochodria passed on to the zygote comes from the cytoplasm of the egg (Instead of the sperm)