Biology chapter 10

gene and locus

A gene is a segment of DNA on a chromosome that describes how to make a certain protein. A locus refers to the location on the chromosome where the gene is found.

Stage of meiosis when crossing over occurs

Prophase 1

The diploid number of chromosomes is found in somatic cell while the haploid number is found in gametes

True

Which genetic disorders is represented with a female who has low or absent fertility and is often short in stature

Turners syndrome

Klinefelter's syndrome is represented as a sex chromosomes combination of

XXY

Most embryos that arise from fusion of gametes with

abnormal chromosome numbers spontaneously abort, but some survive to birth and beyond

The slightly different sequences of a gene are called

alleles

Discuss nondisjunction, along with the genetics, and symptoms associated with: Turner's syndrome

an XO chromosomal condition that affect development in females, at puberty, hormone deficiencies can prevent females from menstruating or developing secondary sexual characteristics. Also, hormone treatment promotes physical development but ca

Discuss nondisjunction, along with the genetics, and symptoms associated with: Klinefelter syndrome

an XXY chromosome that mostly affects males. Usually you have no symptoms, but some may show mixed secondary sexual characteristics, including partial breast development, broadening of the hips, and small tests. Most men are infertile because of low sperm count, but are not impotent

Discuss nondisjunction, along with the genetics, and symptoms associated with: Jacob syndrome

an XYY that affects males. Men with this have high levels of testosterones and ten to develop serve acne, any may be exceptionally tall. This can occur in 1 in every 1,000 males

Stage of meiosis when homologous chromosomes separate

anaphase 1

Stage of meiosis when sister chromatids separate

anaphase 2

Explain how genetic variability arises from crossing over

creates new combo of linked alleles. They can be randomize the lineup and separation of homologous chromosomes in meiotic metaphase 1 and anaphase 1 increase variation. Ex 23 pairs of chromosomes can create gametes with 8 million(2^23) possible combinations of chromosomes.

Cells with pairs of homologous chromosomes are called

diploid

Autosomes have similar appearance and similar DNA sequences and are paired in

diploid cells of both sexes

Explain how genetic variability arises from shuffling homologues

diploid chromosomes each half of a pair of chromosomes can go to either dividing cell

Fusion, taken together with crossing over, ensures that

each human individual is absolutely genetically unique

Explain how genetic variability arises from fusion of gametes

each parent will produce huge numbers of gametes, genetically different in combination of alleles they carry

What is a gamete cell

egg or sperm

Chromosomes that contain the same genes are called

homologous chromosomes, or homologues

Each gene occupies a specific place, or ___ on the chromosome

locus

The genetic variability that occurs from one generation to the next results almost entirely from

meiosis and sexual reproduction

Stage of meiosis when homologous pairs of chromosomes line up with their partner

metaphase 1

Asexual reproduction produces genetically identical offspring by

mitotic cell division

Alleles come from ____, which can occur in two ways

mutations. Cells sometime make mistakes when copying DNA prior to cell division and certain environmental factors can cause mutations.

Meiotic cell division is the key to

sexual reproduction in eukaryotic cells

Meiosis I separates homologous chromosomes into

two haploid daughter nuclei

When gametes unite they form

zygote or fertillized egg that contains thwp sets of chromosomes.

diploid, haploid, and polyploid

Diploid are 2 sets of chromosomes, are homologous .Haploids are single sets of chromosomes sex cells/gametes and are usually half the # of diploids. Polyploidy are containing more than two sets of chromosomes, things like banana, potato and strawberry are examples.

n biological shorthand, the haploid chromosome number is designated n, whereas the diploid number is 2n

In humans, n = 23; 2n = 46

Other organisms may have more than two copies of each homologous chromosome and are

polyploid

If a body cell has 50 chromosomes as the diploid number, how many chromosomes would be in a gamete cell

25

In humans, with 23 pairs of chromosomes, this independent assortment of homologues can create gametes with

8 million (223) possible combinations of chromosomes

autosome and sex chromosome

Autosomes are chromosomes that don't carry any genes that determine the sex of the individual. Sex chromosomes carry sex-determining genes

homologous chromosomes and karyotype

Every chromosome pair represents a set of homologous chromosomes. During sexual reproduction, one chromosome in each homologous pair is donated from the mother and the other from the father. In a karyotype, there are 22 pairs of autosomes or non-sex chromosomes and one pair of sex chromosomes.

Explain how genetic variability arises from mutations

Is the change in the genetic sequence which can happen from cells making mistakes of environmental changes. Ex: DNA copying mistakes in cell division, exposure to ionizing radiation, and infection by viruses

A pic represented of a complete set of chromosomes is called a

Karyotype

When chromosomes fail to separate properly during meiosis leading to an abnormal chromosome number _____ is said to have occurred?

Nondisjunction

sexual reproduction and gametes

Sexual reproduction involves two parents. In sexual reproduction, parents produce reproductive cells—called gametes—that unite to form an offspring. Gametes are haploid cells. This means they contain only half the number of chromosomes found in other cells of the organism; also transmit genetic information from parents to their offspring(sperm and egg cells).

allele and mutation

The whole human family is one species with the same genes. Mutation creates slightly different versions of the same genes, called alleles. These small differences in DNA sequence make every individual unique

Discuss nondisjunction, along with the genetics, and symptoms associated with: Trisomy syndrome

an XXX that mostly affects woman. Usually there is no abnormal symptoms but has an increase chance of learning disabilities and a tendency toward tallness

Twenty-two of the 23 pairs are called

autosomes

Nondisjunction of sex chromosomes in females

can produce eggs that are O or XX eggs instead of eggs with one X chromosome

Meiosis is a specialized

cell division process that produces haploid gametes. Prior to meiosis, the DNA is replicated

Cells in the ovaries and testes undergo meiotic cell division and produce

gametes (eggs and sperm) that have only one member of each chromosome pair. These kinds of cells are called haploid

Haploid cells that are part of the sexual reprpductive cycle are produced by a type of cell division

meiosis

The incorrect separation of chromosomes or chromatids in meiosis is known as

nondisjunction and causes gametes to have too many or too few chromosomes

When normal gametes fuse with these defective sperm or eggs, the zygotes have

normal numbers of autosomes but abnormal numbers of sex chromosomes

Nondisjunction of sex chromosomes in males

produces sperm with either no sex chromosomes (called "O" sperm) or two sex chromosomes (sperm may be XX, YY, or XY)

What does it mean when chromosomes are considered homologous

same size, shape, and gene location

The twenty-third pair are called

sex chromosomes and are different in the male and the female

Eukaryotic chromosomes usually occur in pairs containing

similar genetic information

Genetic variability among organisms is essential for

survival in a changing environment

Sexual reproduction produce offspring through the

union of gametes. These are produced by a specialized form of cell division called meiosis

A diploid cell with paired chromosomes produces haploid daughter cells with

unpaired chromosomes