Lecture Exam 4

Question 1

Mitosis

Answer 1

A diploid cell makes and divides an exact copy of its nucleus.

It is used in cell growth and cell repair.

Mitosis occurs in body cells.

There are four phases:

1. Prophase
2. Metaphase
3. Anaphase
4. Telophase

Question 2

Meiosis

Answer 2

Two nuclear divisions occur to make four haploid cells.

It is used to make gametes (egg and sperm).

Meiosis occurs in sex cells.

It has eight phases (4 in each meiosis, I & II).

Question 3

What creates genetic diversity?

Answer 3

Crossing over during prophase 1

Independent alignment of homologous chromosomes during metaphase 1

Random fertilization

Question 4

Changes in chromosome number

Answer 4

Nondisjunction occurs when both members of a homologous pair go into the same daughter cell during meiosis I, or when sister chromatids fail to separate in meiosis II.

Results of nondisjunction:

Monosomy: cell has only 1 copy of a chromosome e.g., Turner syndrome (only 1 X chromosome)

Trisomy: cell has 3 copies of a chromosome e.g., Down syndrome (3 copies of chromosome 21)

Question 5

Patterns of genetic inheritance basic terminology

Answer 5

Genotype: Specific genes for a particular trait written with symbols

Alleles are alternate forms of a specific gene at the same position (locus) on a gene (e.g., allele for unattached earlobes and attached lobes); alleles occur in pairs.

A dominant gene will be expressed and will mask a recessive gene (Tt or TT).

A recessive allele is only expressed when a gene has two of this type of allele (tt).

Question 6

Patterns of genetic inheritance basic terminology continued

Answer 6

A homozygous dominant genotype consists of two dominant alleles (TT or AA).

A homozygous recessive genotype consists of two recessive alleles (tt or aa).

A heterozygous genotype consists of one dominant allele and one recessive allele (Tt or Aa).

Question 7

Incomplete dominance

Answer 7

Occurs when the heterozygote phenotype is intermediate between phenotypes of the two homozygotes

Example:
(curly hair) CC x cc (straight hair) = Cc (wavy hair)

Question 8

Codominance

Answer 8

Occurs when the alleles are equally expressed in a heterozygote

Example:
(Type A blood) AA x BB (Type B blood) = AB (Type AB blood that has characteristics of both blood types)

Question 9

Multiple allele inheritance

Answer 9

What type of blood would each of the following individuals have in a cross between Ai and Bi?

Possible genotypes: Phenotypes:
AB Type AB blood
Bi Type B blood
Ai Type A blood
ii Type O blood

Question 10

Sex-linked inheritance

Answer 10

Traits are controlled by genes on the sex chromosomes.

X-linked inheritance –the allele is carried on the X chromosome

Y-linked inheritance –the allele is carried on the Y chromosome

Most sex-linked traits are X-linked.

Question 11

X-linked disorders

Answer 11

These are more often found in males than females because recessive alleles are always expressed.

Most X-linked disorders are recessive.

Color blindness is most often characterized by red-green color blindness.

Duchenne muscular dystrophy is characterized by wasting of muscles and death by age 20.

Fragile X syndrome is the most common cause of inherited mental impairment.

Hemophilia is characterized by the absence of particular clotting factors; blood clots very slowly or not at all.

Question 12

Central Dogma

Answer 12

DNA to RNA to Protein

DNA transcripts to RNA which translates to Protein

In the event of reverse transcriptase, RNA can go back to DNA through the process of replication

Question 13

Replication, Transcription and Translation

Answer 13

DNA: AAATAGCCACGT
Complementary DNA: TTTATCGGTGCA
RNA sequence to Comp DNA: AAAUAGCCACGT
tRNA sequence: UUUAUCGGUGCA

Question 14

Gene therapy

Answer 14

Gene therapy –insertion of genetic material into human cells to treat a disorder

In ex vivo therapy, cells are removed from the body for treatment and then reintroduced back into the body.

In in vivo therapy, the vector is introduced directly into the body.

Gene therapy has been most successful in treating cancer.

Question 15

Evolution

Answer 15

Evolution: change in the gene frequency of population or species over time

Adaptation: a characteristic that enables an organism to survive and reproduce in its environment

Question 16

Natural selection

Answer 16

Three vital elements:

1. Variation: There must be physical variations that can be passed from generation to generation
2. Competition: There must be competition for limited resources (food, mates, shelter), and those better adapted will survive and reproduce
3. Adaptation: Individuals with favorable traits survive, reproduce, and pass their traits onto their offspring’s

Question 17

Lamarck vs. Darwin

Answer 17

Lamarck argues that characteristics are acquired over time

Darwin argues that desired characteristics are selected by natural selection

Question 18

Homologous VS Analogous

Answer 18

Analogous:

1. Same function
2. Differ in fundamental structure
3. Different ancestry
4. Example: Wings in bats, birds, insects

Homologous:

1. Different function
2. Similiar in fundamental structure
3. Common ancestry
4. Example: Pentadactyl limb in vertabrates

Question 19

Three domains of life

Answer 19

BACTERIA:
Heterotrophic bacteria
Cyanobacteria

ARCHAEA

EUKARYA:
Protists
Plants
Fungi
Animals

Question 20

Asian and African apes

Answer 20

Humans are most closely related to african apes

Our closest relative is the Chimp

Question 21

Evolution of Hominins

Answer 21

Hominins: All species of the genus Homoand their close relatives

Characteristics:

1. Bipedal
2. Flatter face with a more pronounced chin
3. Brain size
4. Scientists primarily use Bipedal posture as a hallmark of a hominin regardless of the size of the brain to determine relatedness to humans

Question 22

Components of an ecosystem

Answer 22

Ecosystem: A place where organisms interact with each other and their environment

Abiotic components: Nonliving environment

Biotic components: Living components
Autotrophs: Producers
Heterotrophs: Consumers
1. Herbivores: Feed on plants and algae
2. Carnivores: Feed on other animals
3. Omnivores: Eat both plants and animals
4. Detritus feeders: Feed on decomposing organic matter

Question 23

Carbon Cycle