Biology Unit 9: Meiosis and Sexual Reproduction (quiz 3)

mitosis

- 1 division - No recombination - Preserves chromosome # - Daughter cells genetically identical to parent cell

Translocation

- A segment from one chromosome moves to another chromosome - Can fuse genes together - No loss of genetic information, just repositioned ex. Philadelphia translocation - part of chromosome 9 and 22 swap places - Fuses ABL and BCR genes together - Leukemia (cancer of the white blood cells)

Duplication

- Doubling of a chromosome segment - Gene dosage: doubling of genetic information ex. Dup15q Syndrome - Duplication of part of chromosome 15 - Short stature, low muscle tone, seizures - Associated with autism - Low IQ and social skills

Deletion

- One or both ends of a chromosome breaks off - Gene dosage: loss of genetic information ex. Williams Syndrome - Deletion of 26 genes from chromosome 7 - Heart defects and "smiling" facial features - Lack social inhibition ("opposite of autism") - Incredibly empathetic, caring, friendly, unselfish, outgoing - Prone to phobias, low IQ

Inversion

- The segment of chromosome before re-insertion (180° flip) - No loss of genetic information, just reversed gene order ex. Chromosome 9 Inversion - Inversion of a segment of chromosome 9 - Typically no harmful effects - Suspected to cause infertility and/or miscarriages

Changes in chromosome structure

1. deletion 2. duplication 3. translocation 4. inversion

Karyotype

a display of the metaphase chromosomes of a cell (often a somatic cell)

asexual reproduction

advantageous when the environment is stable

Allele

an alternative version of a gene

meiosis produces gametes in what cells

animal

somatic cell

any cell in a multicellular organism except a sperm or egg cell - Often called "body cells", diploid

Which chromosome is the smallest

chromosome 21

Independent Assortment

chromosomes align at random along the metaphase plate during metaphase of meiosis

Mitochondrial Eve

direct, unbroken, maternal line of all currently living humans - 99,000 - 200,000 years ago: first homo sapiens mom Mothers always pass their mitochondria to their offspring

Egg

donates chromosomes, organelles, and stored energy during sexual reproduction

C-value paradox

expectation that the more complex organism, the larger the genome - instead size and complexity don't correlate at all - can vary by as much as 100,000 fold

Nondisjuction

failure of chromosomes to separate correctly during cell division -failure can occur in the first division or the second

Aneuploidy

having an abnormal (non multiple) number of chromosomes -e.g. 47, 48, 52, etc.

Euploidy

having an extract multiple of the haploid number of chromosomes - Humans have 46 chromosomes in their somatic cells

Recombination, if it happens, occurs in ___________ prior to fertilization

individuals

mitosis vs. meiosis

mitosis= identical to parent meiosis= mix of both parents alignment of chromosomes is different in metaphase

Independent assortment

of homologous chromosomes

Sperm

only donates chromosomes during sexual reproduction

Monosomy

only one chromosome, of a pair, is present - 45 chromosomes instead of 46 ex. Turner Syndrome (X -) - present in females. normal intelligence, infertile

Oogenesis

production of eggs - Oocyte cells produce eggs - Only cell in the female body that undergoes meiosis

Spermatogenesis

production of sperm - Spermatocyte cells produce sperm - Only cell in the male body that undergoes meiosis

gametes

sex cells, haploid

meiosis

specialized type of cell division which reduces the chromosome number by half - Parent cells are diploid (2n) - i.e. they have two copies of every chromosome - Meiosis produces haploid cells (n) also known as gametes - i.e. they have one copy of every chromosome -2 divisions -recombination - Halves chromosome # - Daughter cells genetically different from parent cell

Gene Dosage

the # of copies of a given gene present in the cell of an organism -- Any gene* present in any other copy number (1, 3, 4, etc.) can have severe side effects

sexual reproduction

the creation of genetically unique offspring by the fusion of two gamete cells - Two parents required - Both parents must have compatible genomes -advantageous when the environment changes

Recombination (crossing over)

the exchange of genetic material between homologous chromosomes during meiosis

Trisomy

three copies of he same chromosome, instead of two - 47 chromosomes instead of 46 - 21 and X chromosome most common ex. Down Syndrome (21) - short stature - flat face -learning impairment -occurrence increases with mother's age

Homologous chromosomes

two chromosomes that make up a matched pair in a somatic (body) cell - 1 chromosome from your mom, 1 chromosome from dad - Each chromosome contains the same genes but not necessarily the same alleles