Bio Exam 3

Question 1

• Mitosis

Answer 1

the division of the genetic material in the
Nucleus

Question 2

• Stages of Mitosis

Answer 2

Prophase- Breaks down and builds structures up, Chromosomes begin to condense

Metaphase- Chromosomes are lined up at metaphase plate, Kinetochores are attached to the microtubules from
opposite poles, Spindle checkpoint

Anaphase- Sister chromatids separate and are pulled to the opposite ends of the cell

Telophase & Cytokinesis- Cell division is close to complete, Structures are re-established while others are broken down, Chromosomes decondense, Cytokinesis

Question 3

mitotic spindle

Answer 3

structure made of microtubules that controls chromosome movement during mitosis.

Question 4

Meiosis

Answer 4

• The chromatids are sorted into four haploid daughter cells

Question 5

The stages of meiosis 1

Answer 5

Prophase I- In early prophase I, each chromosome pairs with its homolog and crossing over occurs, X-shaped regions called chiasmata are sites of crossovers
~Metaphase I- In metaphase I, pairs of homologs line up at the
metaphase plate, with one chromosome facing each pole
~Anaphase I- In anaphase I, pairs of homologous chromosomes separate, Sister chromatids remain attached at the centromere and move as one unit toward the pole
~Telophase I and cytokinesis- In the beginning of telophase I, each half of the cell has a haploid set of duplicated chromosomes, each chromosome still consists of two sister chromatids, Cytokinesis usually occurs simultaneously, forming two haploid daughter cells

Question 6

• Stages of meiosis 2

Answer 6

prophase II - In prophase II, a spindle apparatus forms
~ metaphase II - In metaphase II, the sister chromatids are arranged at the metaphase plate, The kinetochores of sister chromatids attach to microtubules extending from opposite poles
~anaphase II- In anaphase II, the sister chromatids separate,
The sister chromatids of each chromosome now move as
two newly individual chromosomes toward opposite poles
~telophase II and cytokinesis- In telophase II, the chromosomes arrive at opposite poles, Nuclei form, and the chromosomes begin decondensing, Cytokinesis separates the cytoplasm

Question 7

Explain the differences between cytokinesis between plant and animal

Answer 7

• In animal cells, cytokinesis occurs by a process known as cleavage
• In plant cells, a cell plate forms during cytokinesis

Question 8

Identify the difference between chromosomes, sister chromatids, homologous chromosomes

Answer 8

Chromosomes- string of DNA wrapped around associated proteins that give the connected nucleic acid bases a structure.
- Sister chromatids- Two copies of a duplicated chromosome attached to each other by proteins at the centromere and, sometimes, along the arms. While joined, two sister chromatids make up one chromosome. Chromatids are eventually separated during mitosis or meiosis II.
- Homologous chromosomes- A pair of chromosomes of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding loci.

Question 9

• Difference between centrosome and centromere

Answer 9

• Centrosome- A structure present in the cytoplasm of animal cells that functions as a microtubule-organizing center and is important during cell division. A centro-some has two centrioles.
• Centromere- In a duplicated chromosome, the region on each sister chromatid where it is most closely attached to its sister chromatid by proteins that bind to the centromeric DNA. Other proteins condense the chromatin in that region, so it appears as a narrow “waist” on the duplicated chromosome. (An unduplicated chromosome has a single centromere, identified by the proteins bound there.)

Question 10

• Identify the sex chromosomes

Answer 10

• A chromosome responsible for determining the sex of an individual. males contain one X and one Y chromosome, while females contain two X chromosomes. Thus, males are considered heterogametic – they can produce two different types of gametes, depending on whether the sperm carries an X or a Y chromosome. Females are homogametic – all their eggs carry one X chromosome.

Question 11

• Natural selection

Answer 11

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

Question 12

• Law of segregation

Answer 12

Mendel’s first law, stating that the two alleles in a pair segregate (separate from each other) into different gametes during gamete formation.

Question 13

• Independent assortment

Answer 13

Mendel’s second law, stating that each pair of alleles segregates, or assorts, independently of each other pair during gamete formation; applies when genes for two characters are located on different pairs of homologous chromosomes or when they are far enough apart on the same chromosome to behave as though they are on different chromosomes.

Question 14

• Codominance

Answer 14

The situation in which the phenotypes of both alleles are exhibited in the heterozygote because both alleles affect the phenotype in separate, distinguishable ways.

Question 15

• Complete dominance

Answer 15

The situation in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable.

Question 16

• Incomplete dominance

Answer 16

The situation in which the phenotype of heterozygotes is intermediate between the phenotypes of individuals homozygous for either allele

Question 17

• Understand what chromatin is and what it consists of

Answer 17

• The complex of DNA and proteins that makes up eukaryotic chromosomes. When the cell is not dividing, chromatin exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope.

Question 18

genome

Answer 18

• The genetic material of an organism or virus; the complete complement of an organism’s or virus’s genes along with its noncoding nucleic acid sequences

Question 19

diploid

Answer 19

A cell containing two sets of chromosomes (2n), one set inherited from each parent

Question 20

• Haploid

Answer 20

A cell containing only one set of chromosomes (n).

Question 21

• Monohybrid

Answer 21

An organism that is heterozygous with respect to a single gene of interest. All the offspring from a cross between parents homozygous for different alleles are monohybrids. For example, parents of genotypes AA and aa produce a monohybrid of genotype Aa.

Question 22

• Dihybrid

Answer 22

An organism that is heterozygous with respect to two genes of interest. All the offspring from a cross between parents doubly homozygous for different alleles are dihybrids. For example, parents of genotypes AABB and aabb produce a dihybrid of genotype AaBb.