Meiosis

Genes

Unit of inheritance passed onto offspring

Three parts of Nucleic Acid

N-base, Pentose sugar, phospate group

2 types of Nucleic Acids

DNA and RNA

Two families of nitrogen bases w types

Purines(A+G) and pyrimidines(C+U+T).

How do the purines/pyrimidines bind?

A+T is two bonds, C+G is three bonds

Difference between Deoxyribose and ribose?

Deoxyribose is in DNA lacking one oxygen on carbon-2 while Ribose is in RNA with the oxygen on carbon-2.

Heredity

Transmisison of traits from one generation to the next.

Humans contain __ chromosomes in their somatic cells, and __ in their gametes.

46,23

Human genome

The complete set of genetic information for a human being, consisting of all the DNA stored in the 2323 pairs of chromosomes in the nucleus plus mitochondrial DNA. Approx 20,000 genes total, one chromosome as 100s to 1,000s of genes on it.

Locus

A gene’s specific location on the chromosome.

Why and how is DNA’s message transcribed?

DNA is too big to exit the nucleus, so it relies on mRNA to transcribe or carry DNA’s message out of the nucleus.

How is DNA’s message translated?

mRNA arrives at a ribosome where the message gets translated into the making of a protein.

Reproduction that brings about genetically identical clones

Asexual reproduction

Number of chromosomes from each parent

23

Karyotype

When chromosomes are arranged in pairs starting with the longest

Homologs/Homologous pairs/chromosomes/tetrads

Chromosomes that carry the same traits

Alleles

one of two or more alternative forms of a gene that arise by mutation and are found at the same loci on a chromosome.

Autosomes

22 pairs of non-sex chromosomes in humans

Number of inherited chromomes

23

Haploid

having a single set of unpaired chromosomes.(1n)

Diploid

containing two complete sets of chromosomes, one from each parent.(2n)

Zygote

single-celled organism formed when a sperm fertilizes an egg

If you want to take a 2n down to a 1n, the process that halves chromosome numbers is _____.

Meiosis

Meiosis results in how many divisions and how many daughter cells?

2,4

Synapsis

Pairing of homologous chromosomes during prophase I so that crossing over can occur

Mitosis

• S-phase

• 1

• No

• 2, identical

• growth + tissue repair

Meiosis

• S-phase

• 2

• yes, prophase I

• 4, different

• produce gametes

Independent Assortment

This means that when homologues line up at the equator of the cell in metaphase I, it is an “independent”/ random event for each homologous pair.

Crossing Over

Occurs during prophase I of meiosis when homologues come together during synapsis to form homologs. Then, non sister chromatids trade places.

Chiasmata

The regions created from crossing over

Random Fertilization

Refers to the fact that each parent has 8 million possible ovules/sperm cells.

What creates the greatest number of new genetic combinations?

mutations