Cytogenetics L2

Human genetics

molecules that carry heriditary information

Nucleotides

Basic units of DNA molecule, composed of a sugar, a phosphate, and one of 4 DNA bases

DNA structure

double helix stabilized by hydrogen bonds

DNA founders

Watson and Crick Ft. Rosalin Franklin

DNA always follows what rule

5' - 3'

Nitrogenous bases in DNA

adenine, guanine, cytosine, thymine

Purines

Adenine and Guanine

Pyrimidines

Cytosine and Thymine

Erwin Chargaff's Rule

Not all nitrogenous bases are proportional, but all complementary bases are equal

RNA does not follow this rule

5' - 3'

RNA nitrogenous bases

Adenine, Guamine, Uracil, Cytosine

mRNA

type of RNA that carries instructions from DNA in the nucleus to the ribosome

rRNA

type of RNA that makes up part of the ribosome

tRNA

type of RNA that carries amino acids to the ribosome

Codon

A specific sequence of three adjacent bases on a strand of DNA or RNA that provides genetic code information for a particular amino acid

DNA

Central dogma of protein synthesis

Protein

chain of amino acids

DNA replication

the process of making a copy of DNA; occurs through the nucleus

Transcription

synthesis of an RNA molecule from a DNA template; occurs in the nucleus

Translation

Process by which mRNA is decoded and a protein is produced; occurs in the Ribosome,

chain of amino acids is synthesized, 64 possible codons

What kind of bond is in RNA

peptide bond

mRNA processing

some nucleotides are removed, addition of a 5' cap

tRNA anticodon

UAC

start codon

AUG

stop codon

UAA, UAG, UGA

DNA

First level of condenstation

DNA organization

Octamer, 8 histones, 2 molecules, 2 H2A, 2H2B, 2H3, 2H4

Process of DNA to chromosome

Dna > Nucleosome bead > Solenoid > Chromosome

4 types of chromosomes

metacentric, submetacentric, acrocentric, telocentric

Telomere

DNA at the tips of chromosomes

unique-sequence DNA

Sequence present only once or a few times in a genome. 75% of chromosome

Repetitive DNA

present in multiple copies in the genome. 25% of chromosome

highly repetitive DNA

(>105) alpha satellite DNA

middle repetitive DNA

(102-104) minisatellites

Euchromatin

loosely packed chromatin, transcriptionally active

Heterochromatin

highly condensed chromatin, transcriptionally inactive

constitutive chromatin

Region of heterochromatin that is never transcribed, distal end of Y chromosome

faculative chromatin

can be reverted back to U chromatin

Mitosis

somatic cell division

Meiosis

gametic cell division

Interphase

period of the cell cycle between cell divisions

G1 phase

9 hours, metabolically active

Synthesis

5 hours

G2 phase

3 hours, undergoes cell division

Prophase

Begins to coil

Metaphase

Chromosomes line up in the middle of the cell

Anaphase

Sister chromatids are pulled apart to opposite poles.

Telophase

Division, Cleavage forms, chromosome uncoils, uncondenses

cyokenisis

The division of the cytoplasm and cell organelles

Meiosis.

2 identical cells with 23 chromosome, haploid, in ovaries or testes

Meiosis I

46 chromosomes

leptotene

chromosomes condense

Zygotene

synapsis begins, threadlike structures appear

Pachytene

synapsis complete, crossing over

Diplotene

chromosomes begin to uncoil

Diakinesis

nuclear envelope fragments, chromosomes complete condensing, tetrads ready for metaphase.

Metaphase I (Meiosis)

disapearance of nuclear membrane

Anaphase I (Meiosis)

centromeres seperate and migrate

Telophase I (Meiosis)

Seperation

Spermatogenesis

the production of sperm cells

Oogenesis

Begins in pre-natal life, for females