Prin Of Gen Exam 1

Mitosis

the process of cell division that results in two identical daughter cells from a single parent cell in somatic cells

Interphase, prophase, metaphase, anaphase, and telophase

Stages of mitosis in order

Interphase

initial stage of the cell cycle; cell spends the most amount of time here

Prophase

longest phase of mitosis; centrioles migrate to opposite ends of the cell to establish poles

Metaphase

 chromosomes line up at the middle of the cell; produces spindle fibers

Anaphase

spindle fibers pull chromosomes apart at the centromeres; half sister chromatids moves in opposite direction

Telophase

final stage; cytokinesis divides the cytoplasm of the cells into two

Chromatin during ______ is replicated; unwound chromosome located in nucleus

Interphase

Sister chromatids held together at the centromere during _______

prophase

____ new identical daughter cells are formed containing 2N number of chromosomes during _______

Two, Telophase

Meiosis

 occurs in gametes or sex cells to produce daughter cells with half the number of chromosomes as usual

______ has two cell divisions, resulting in 4 genetically unique daughter cells

Meiosis

Interphase, Prophase 1, Metaphase 1, Anaphase 1, Telophase 1, Prophase 2, Metaphase 2, Telophase 2

Stages of meiosis in order

Crossing Over

During prophase 1 replicated homologous pairs of chromosomes come together in a process called synapsis, where sections of chromosomes are exchanged

Where does mitosis occur

In body cells

Where does meiosis occur

in testes and ovaries (sex cells)

What is the final product in mitosis

2 diploid cells

What is the final product in meiosis

Four gametes haploid cells

IF AN ORGANISM HAS A DIPLOID NUMBER OF 16, HOW MANY CHROMATIDS ARE VISIBLE AT THE END OF MITOTIC PROPHASE?

32

Metacentric

The centromere is located approximately in the middle, dividing the chromosome into two equal arms.

Acrocentric

The centromere is positioned very close to one end, resulting in a very short p-arm.

Telocentric

The centromere is located at the very tip or end of the chromosome

True Breeding

parents whose offspring are identical for a certain trait

Reciprocal cross breeding

designed to test the role of sex on the inheritance pattern

Postulate 1

 a specific unit factor exists for each trait, receiving one factor from dad and one from mom

Postulate 2

 when two different unit factors are present for an individual, one factor is dominant to the other

Postulate 3

 during meiosis, the paired unit factors separate/segregate randomly

Gene

the modern term for mendel's “unit factors” unit of inheritance 

Allele

Alternative form of a gene

Test Crossing

 taking an individual with an unknown genotype and crossing it with a known genotype (homozygous recessive)

Postulate 4

 pairs of contrasting traits are inherited independently

Homogametic

sex-produce uniform gametes (ex. Females in mammals)

Heterogametic

sex-produce unlike gametes (ex. Males in mammals)

Monohybrid Cross

¾ dominant ¼ recessive

When answering a chi-square what must you include

Full chi-square table, degrees of freedom, null hypothesis, conclusion fail to reject or reject

Incomplete or Partial Dominance

 when a cross between two parents with different phenotypes produces an intermediate phenotype; neither parental allele is dominant

Codominance is only in a ________

heterozygote

Hemizygous

 males cannot be homozygous or heterozygous for x-linked genes because they only have one copy of the x chromosomes

Sex chromosomes in birds

Female-ZW Male-ZZ

Sex Linked traits

Traits that are located on the sex chromosomes only, x linked in humans/mammals and z linked in birds, males in humans/mammals and females in birds only have one allele for each gene, not two

Sex Limited inheritance

Occurs on autosomal chromosomes, NOT the sex chromosomes, Expression of a specific phenotype is absolutely limited to one sex, Expression of the gene is turned off in one of the sexes despite having the same genotype, Responsible for sexual dimorphism-observable differences between sexes

Sex Influenced Inheritance

Occurs on autosomal chromosomes, NOT the sex chromosomes, The sex of the individual influences the expression of a phenotype that is not limited to one sex or the other, The expression of the gene in sex influenced traits is influenced by a hormonal or anatomical difference between sexes, Heterozygous genotype exhibits one phenotype in one sex and contrasting one in the other , An allele may be expressed as a dominant in one sex and recessive in the other

Primary First Division Nondisjunction

 failure of paired homologous chromosomes (tetrad) to separate during the first meiotic division

Secondary Second Division Nondisjunction

failure of sister chromatids to divide during the second meiotic division

What is the result of First Nondisjunction

Results in both trisomy and monosomy

What is the result of Second Nondisjunction

Results in all 3 conditions-trisomy,disomy, and monosomy

Result of Nondisjunction

Egg or sperm cell can lose a sex chromosome resulting in a daughter with only one X chromosome

Aneuploidy

the abnormal condition where one or more chromosomes of a normal set of chromosomes are missing or present in more than their usual number of copies

Monosomy X-Turner Syndrome

1st Type of chromosomal # abnormality, characterized by short stature, unable to conceive, kidney problems

Trisomy 21 Downsyndrome

2nd type of chromosomal # abnormality

Disomy

No loss or gain of chromosomes have occurred-normal meiotic division

Lethal Alleles

Genes which result in viability reduction of an individual or become a
cause of death to individuals carrying them