Biology: Concepts and Connections, 7th Edition, Chapter 8-11 to end

Chiasma

(greek for cross) The sites of crossing over appear as X-shaped regions. A place where two homologous (non sister) chromatids are attached to each other.

Locus

(plural- loci) A particular place on the chromosome

In metaphase of mitosis, each chromosome contains how many chromatids?

2 sister chromatids

The haploid number for humans is

23, n=23

A human cell at metaphase contains how many sets of duplicated chromosomes?

23, they occur in matched pairs

The total number of combinations of chromosomes that meiosis can package into gametes for any species is

2^n, n=haploid number

For humans the diploid number is

46, 2n=46

Which of the following statements regarding prokaryotes is false?

Prokaryotic chromosomes are more complex than those of eukaryotes

Crossing over begins very early in what phase of meiosis?

Prophase I

Duplicated homologous chromosomes pair to form tetrads in what phase?

Prophase I

Tetrads

Sets of four chromatids, with each pair of sister chromatids joined at the centromeres

Homologous chromosomes come together as pairs in a process

Synapsis, In prophase I

At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.

Telophase I

Autosomes

The 22 remaining pairs of chromosomes found in males and females.

Translocation

The attachment of a chromosomal fragment to a non homologous chromosome. May be reciprocal: two non homologous chromosomes may exchange segments

Trisomy 21

The basis of Down syndrome

The total number of chromosomes is called

The diploid number (2n)

Meiosis

The production of egg and sperm cells involves a special type of cell division. Produces haploid gametes in diploid organisms

Genetic Recombinant

The production of gene combinations different from those carried by the original parental chromosomes.

Life cycle

The sequence of stages leading from the adults of one generation to the adults of the next.

With the exception of identical twins, siblings who have the same two biological parents are likely to look similar, but not identical, to each other because they have

a similar but not identical combination of genes.

Karyotypes

are often produced from dividing cells arrested at metaphase of mitosis

Strictly speaking, the phrase "like begets like" refers to

asexual reproduction only

Because in meiosis, one duplication of chromosomes is followed by two divisions, each of the four daughter cells produced

has a haploid set of chromosomes and are not genetically identical

Chronic myelogenous leukemia (CML)

is one of the most common leukemias,affects cells that give rise to white blood cells (leukocytes), and results from part of chromosome 22 switching places with a small fragment from a tip of chromosome 9.

Nondisjunction can happen if

meiosis I, if both members of a homologous pair go to one pole or meiosis II if both sister chromatids go to one pole.

In meiosis, how many crossover events occur per chromosome pair?

one to three

During _____ a spindle forms in a haploid cell.

prophase I

Alterations of chromosome structure can cause

Birth defects and cancer

The site of attachment and crossing over.

Chiasma, Nonsister chromosomes join here

Homologous Chromosomes

Chromosomes that have twins resembling its length and centromere position. Two chromosomes of matching pairs both carrying genes controlling the same inherited characteristics.

Nonsister chromatids exchange genetic material in a process

Crossing over

Which of the following statements regarding the differences between mitosis and meiosis is false?

Crossing over is a phenomenon that creates genetic diversity during mitosis.

The sources of genetic variability therefore include

Crossing over, Independent orientation of chromosomes, and Random fertilization

If a fragment of a chromosome is lost or removed, the remaining chromosome will then have a ______.

Deletion

Turner syndrome

Denoted as XO, Lacking one X chromosome, Are females and sterile because their sex organs are underdeveloped. Individuals usually have a short statue and a web of skin between the neck and shoulders

Klinefelter syndrome

Denoted as XXY, Have a extra X chromosome, Individuals are males, but testes are abnormally small and individuals are sterile. Often includes breast enlargement, and other female body characteristics

Sex Chromosomes

Determines an individual's sex

If a fragment from one chromosome joins to a sister chromatid or homologous chromosome, it will produce a ______

Duplication

What gender has fully homologous chromosomes?

Females (XX)

What are the three major checkpoints in a cell cycle?

G1, G2, M

Each _____ has a single set of chromosomes, 22 autosomes plus a sex chromosome. (X or Y)

Gamete

_____ are made by a special sort of cell division called _____, which occurs only in reproductive organs.

Gametes, Meiosis

Which of the following statements regarding genetic diversity is false?

Genetic diversity is enhanced by mitosis.

Each daughter cell produced by meiosis II has only one ______ set of chromosomes.

Haploid

What type of chromosome pairs have different versions of the same gene?

Homologous

Diploid

Humans, animals, many plants are considered this because all body cells contain pairs of homologous chromosomes.

Genetic variation in gametes results from

Independent orientation at metaphase I and random fertilization.

Three sources of genetic variability in sexually reproducing organisms

Independent orientation of chromosomes at metaphase I, random fertilization, and crossing over during prophase I or meiosis.

If a fragment reattaches to the original chromosome but in the reverse orientation.

Inversion

f a chromosome fragment breaks off and then reattaches to the original chromosome, but in the reverse direction, the resulting chromosomal abnormality is called a(n)

Inversion

What type of blood cell is used to prepare a karyotype?

Lymphocytes

Chromosomes X and Y behave as a homologous pair in

Meiosis

_____ prevents each generation from having twice as much genetic material as the generation before

Meiosis

_____ reduces the chromosome number from diploid to haploid.

Meiosis

All events unique to meiosis happens in

Meiosis I

A human in what phase contains 23 sets of duplicated chromosomes.

Metaphase

All the chromosome pairs orient independently at what phase?

Metaphase I

Tetrads align at the cell equator in which phase?

Metaphase I

Tetrads are aligned at the metaphase plate in what phase?

Metaphase I

During _____ chromosomes align single file along the equator of a haploid cell.

Metaphase II

Meiosis II is virtually identical to _____ because the separate sister chromatids

Mitosis

_____ produce daughter cells with the same number of chromosomes as the parent cells, _____ reduces the chromosome number by half.

Mitosis, meiosis.

XXX

Most are normal females with an extra X chromosome

XYY

Most are normal males with an extra Y chromosome (although they tend to be taller than average)

Whats ultimately responsible for genetic diversity in living organisms?

Mutations

Haploid

A cell with a single chromosome set; has only one member of each homologous pair.

Karyotype

A photographic inventory of an individual's chromosomes arranged in pairs. Shows them condensed and doubled as appeared in metaphase of mitosis

Somatic Cell

A typical body cell has 46 chromosomes

Crossing over

An exchange of corresponding segments between nonsister chromatids of homologous chromosomes

Nondisjunction

An occasional mishap in which the members of a chromosome pair fail to separate.

Homologous chromosomes migrate to opposite poles during _____.

Anaphase I

Pairs of homologous chromosomes separate, sister chromatids of each chromosome stay together in what phase?

Anaphase I

Within one chromosome, what is the relationship between the sequence of bases in DNA of one sister chromatid compared to the other?

The sequences are identical.

Gametes

The sperm and egg cells

, there is no chromosome duplication between the end of meiosis I and the beginning of meiosis II. T/F?

True

At the end of meiosis I, There are _____ cells, with each chromosome still having two _____ _____.

Two, sister chromatids

When does the abnormal behavior of a cancer cell begin?

When a normal cell is converted into a cancer cell

When animal cells are grown in a petri dish, they typically stop dividing once they have formed a single, unbroken layer on the bottom of the dish. This arrest of division is an example of

density-dependent inhibition.

When the cell cycle operates normally, mitosis produces genetically identical cells for

growth, replacement of damaged and lost cells, and asexual reproduction.