Genetics 1 Flashcards
Garrod
new class of human disease based on hereditary factors (inborn errors of metabolism)
Mendel
father of modern genetics (hybridization of peas)
watson and crick
double helix DNA
human genome project
2003, sequence of human genome completed revealing all 3 billion base pairs
what does the human genome include
human genome encoded on both nuclear and mitochondrial chromosomes contained in the nucleus of somatic cells
soma=
body
how many chromosomes ?
46 chromosomes (22 pairs of autosomes, 1 pair sex chromosomes)
what are homologous chromosomes
members of a pair of chromosomes
- carry matching genetic information
- same genes in the same sequence
what are alleles
identical or slightly different forms of the same gene
what is a locus
specific location of a gene or DNA sequence on a chromosome
DNA structure is made up of
polymeric nucleic acid macromolecule (nucleotide)
what 3 types of units is DNA made of
- 5 carbon sugar (deoxyribose)
- nitrogen containing base
- phosphate group
purine bases
- adenine (A)
- guanine (G)
pyrimidine bases
- cytosine (C)
- thymine (T)
DNA polynucleotide chain characteristics
- polymerized (linked, connected together) by 3’-5’ phosphodiester bonds
- right handed double helix held together by H bonds
characteristics of chromosomes
complexed with several classes of chromatin proteins (histone and nonhistone proteins)
how are chromosomes packaged?
as chromatin
functional organization and structural organization of genome
highly correlates
out of 3 billion base pairs of DNA in the genome, how many code for proteins
less than 1.5%
what percent of base pairs codes for regulatory elements of gene expression
about 5%
what percent of base pairs in genome codes for so called single-copy or unique DNA
half the total linear length of the genome
estimated 25,000 genes in the genome fall under the single copy DNA category
what percentage of base pairs in genome code for repetitive DNA
about half of the genome
-about half consists of repetitive DNA- involved in maintaining chromosome structure and source of variation
mitosis
- ordinary somatic cell division
- involved with body growth, differentiation, tissue regeneration
- results in two daughter cell with chromosomes and genes identical to parent cell
- 2n, diploid
meiosis
- involves the cell of the gremlin
- formation of reproductive cells (gametes)
- n, haploid
interphase=
G1 + S + G2
- period between the 2 mitoses
- state in which most of the life cycle of a cell is spent
phases of cell cycle and how much time in each
G1 (10-12 hrs)
S (6-8hrs)
G2 (2-4 hrs)
M (1-2 hrs)
G1 phase
10-12 hours, up to days to years
- no DNA synthesis
- neurons and RBC get arrested in this state of differentiation
S phase
6-8 hours
- DNA synthesis
- replication to form 2 sister chromatids
G2 phase
2-4 hours
-doubling of total mass
M phase
mitosis
1-2 hours
mitosis
prophase
- initiation of mitosis
- condensation of chromosomes, formation of mitotic spindles an centrosomes
mitosis
prometaphase
- breakup of nuclear membrane
- establish connection to kinetochores
- chromosomes begin to congregate midway
mitosis
metaphase
- chromosomes reach maximum condensation
- arranged and lined up at the equator
mitosis
anaphase
- chromosomes separate at the centromere
- sister chromatid become separate and independent
- movement to opposite poles
mitosis
telophase
- decondense
- nuclear membrane begins to reform
meiosis is
cell division that involves the germ line
-whereby diploid cells give rise to haploid gametes
meiosis consists of
- 1 round of DNA synthesis and 2 rounds of chromosome segregation and cell division
- meiosis I and meiosis II
meiosis I and II
meiosis I is reduction division- chromosome number is halved
-recombination (meiotic crossover) occurs
meiosis II is ordinary mitosis
recombination
(meiotic crossover) homologous segments of DNA are exchanged between non-sister chromatids of a pair of homologous chromosomes
