Biol exam 2

the cell cycle

1. Interphase (between cell division) 2. Mitotic phase (cell division phase) takes 18-24 hours mitosis and cytokinesis takes less than an hour

Mitotic phase (cell cycle)

1. Mitosis phase(nuclear division, duplicated chromosomal DNA is distributed between two daughter nuclei) 2. Cytokinesis (cytoplasm divide, two new daughter cells formed)

Karyotype

A composite visual display of all of the chromosomes of an individual

Monozygotic twins

Can occur by embryo splitting at 2 cell stage day 2 4 cell stage day 4 8 cell stage day 6

Genes

DNA sequences that contain instructions for building proteins physical entities

Mendel's law of segregation (1860s)

Each characteristic of a diploid organism is controlled by two gene alleles

The two fertility techniques "in vitro fertilization" (IVF) and "gamete intrafallopian transfer" (GIFT) are fundamentally different in that:

Embryos are conceived outside the body when the fertility technique of "in vitro fertilization" is used.

True or False? Hemophilia is strictly a male disease.

False

M checkpoint

Known as spindle checkpoint Are all the sister chromatids correctly attached to the spindle microtubules Look for "straggler" chromosomes that are in the wrong place

Which one of the following statements is TRUE regarding the G0 phase of the cell cycle?

Neurons and osteocytes remain in G0 after adolescence

Two-trait crosses:

Outcome of two-trait crosses can be predicted by Punnett square analysis

Polygenic Inheritance

Phenotype is influenced by many genes ( height, body size, body shape)

Deletions

Piece of a chromosome breaks off- genes are now missing

Translocations

Piece of chromosome breaks off and attaches to a different chromosome

"Bell shaped curve"

Polygenic traits that are usually distributed within a population as a continuous range of values

Differentiation

Process by which a cell becomes different from its parent or sister cell

Which two phases of mitosis are essentially mirror images of each other?

Prophase and telophase

Chromosomes are reproduced in which phase of the cell cycle?

S (the DNA and chromosomes are duplicated during the S phase of interphase)

Law of independent assortment

The alleles of different genes are distributed to gametes independently during meiosis This law applies only if the two genes in question are on different chromosomes

G2 Checkpoint

The cell will check for DNA integrity (is any DNA damaged) and DNA replication(was the DNA completely copied during S phase)

G1 checkpoint

The main decision point for a cell Once the cell passes the G1 checkpoint and enters S phase, it becomes irreversibly committed to division Cell monitors: size, nutrients, molecular signals, DNA integrity

Interphase (cell cycle)

a. G(1)- primary growth phase b. S - synthesis of DNA for next cell division c. G(2) - final growth phase before division

sex-influenced traits

affected by actions of sex genes genes encoding these traits are located on the autosomes Expression of the trait is affected by the presence of testosterone, estrogen

Cell differentiation of a human pre-embryo begins:

after the 8-cell stage.

Variations of homologous genes that result in differences in structure and function are:

alleles

Alleles:

alternative forms of a gene Alleles arise from mutation Milk digestibility, freckles

Genotype

an individual's complete set of alleles

Which one of the following stages of mitosis is shown in the figure above, and which stage comes next?

anaphase, telophase

Codominance

both gene products are equally expressed (genes for ABO blood types, sickle-cell gene )

Which of the following human traits is an example of codominance?

both sickle-cell anemia and AB blood type

Multicellular organisms

cell division enables growth from a fertilized egg to a multicellular individual

Unicellular organisms

cell division is the mechanism of reproduction

The process by which cells become specialized from one another is called:

differentiation

pluripotent

each cell has the ability to become any type of cell in the body

Genes

encode specific proteins

Alleles are alternative versions of chromosomes.

false

Genotype and phenotype always match

false

Linked genes are not influenced by crossing-over during meiosis.

false

Monozygotic twins, each have a separate placenta.

false

A person with one copy of the sickle-cell gene has the disease.

false - the gene is recessive so it requires two

The result of mitosis is the production of two daughter cells that are genetically identical to each other but not to the parent cell.

false - they are also identical to parent cell

zygote

fertilized egg cell

The law of segregation states that:

genes separate from each other during gamete formation so that each sperm and egg receive only one allele from each pair.

proteins

have specific functions leading to phenotypes

Incomplete dominance

heterozygous phenotype that is a blend of the two homozygous phenotypes (wavy hair)

If both alleles of a particular gene are identical, the person is said to be:

homozygous

Which one of the following genetic disorders is caused by the inheritance of a dominant-lethal allele?

huntington's disease

The offspring resulting from a cross between a nearly white horse (cc) and a chestnut-colored horse (CC) is of an intermediate color (between white and chestnut). Which one of the following patterns of inheritance best explains this?

incomplete dominance

A drug that interferes with the development and function of microtubules would interfere with:

metaphase and anaphase of mitosis.

In polygenic inheritance:

multiple alleles and genes contribute to a phenotype.

Phenotype

observable physical traits (hair color)

Linked alleles:

physically located on the same chromosome

Chromosomes first become visible as two sister chromatids held together at the centromere during which one of the following phases of meiosis?

prophase

Mitosis differs from meiosis in that only mitosis:

results in cells that are genetically identical to the original cell.

Which one of the following cell types typically divide throughout one's life?

stem cells in the bone marrow

Genome

sum total of all of an organism's DNA

Alterations in chromosome number can occur with any chromosome, but most alterations are not seen in human populations because:

they are lethal during fetal development.

When a piece of chromosome breaks off and reattaches at another site on the same or another chromosome, this is called:

translocation

If alleles for the same gene are different in the same person, that individual is heterozygous for the trait.

true

In the human male, genotype and phenotype associated with the genes on the X chromosome are determined by the one X chromosome he inherits from his mother.

true