UNIT TWO Flashcards
what is genetics?
the study of the inheritance of observable traits and their effect5s on species
what is molecular genetics?
the study of the processes of transferring genetic information from genotype to phenotype
what is DNA structure?
sugar-phosphate gross “ribbons” in an antiparallel double helix
nitrogenous bases form “rungs of the ladder” by bonding complimentarly (A-T G-C)
what is the structure of a eukaryotic chromosome?
P telomere
A telomere
centromere (constricted region of chromosome)
what is a homologous chromosome?
chromosomes with the same shape, size, and genes, but aren’t identical
(present in G1 before DNA replication)
how is DNA organized?
DNA joined with histones to create fibres of histones and DNA that make bigger fibres and eventuallly chromatids and then eventually chromosome
what are the stages of mitosis?
G1,S,G2
prophase
prometaphase
metaphase
anaphase
telophase
what happens in G1, G2, and S phase?
G2 has a check, S phase produces sister chromatids (two identical DNAs joined at centromere)
what happens in prophase?
centrosomes move apart and chromosomes condense and attach to each other and spindle forms
what happens in prometaphase?
nuclear envelope is gone, spindle can now interact, centrosomes form the two poles of the cell
what happens in metaphase?
chromosomes align on metaphase plate (pulled apart by spindle)
what happens in anaphase?
all chromosomes attach, sister chromatids are separated to form daughter chromatids
what happens in telophase?
nuclear envelope reforms, chromsomes uncompact, the two original alleles are kept
how does sexual reproduction work?
gametes (eggs/sperm) contain a haploid of chromsomes
fusion of the haploids form a diploid cell (fertilization)
zygote is produced with two copies of each chromosome
what does meiosis do?
reduces diploid (2N) to haploid (1N) to produce gametes (separates homologous chromosomes which introduced genetic variation)
what happens in the stages of meisosis?
interphase - duplicates pair of chromsomes
meisosis I - homologous chromosomes separate to form haploid cells
meisosis II - sister chromatids separate
what was believed before mendelian inheritance?
a “blending hypothesis” (Mendelian propose “particulate” hypothesis
Darwinian theory of natural selection is dominant by end of 19th century
what is Mendel’s first law?
Segregation of Alleles:
two alleles separate during gamete formation and end up in different gametes
what is Mendel’s second law?
Independent Assortment of Genes:
one gene’s alleles will segregate independent of another gene’s alleles
what are the deviations from Mendel’s laws?
- traits on the same chromosomes
- traits on sex chromosomes
- incomplete dominance
- multiple alleles
- codominance
- lethal alleles
what is a karyotype?
a display of homologous chromsomes arranged by size and shape
what are the two types of chromosomes?
autosomal chromosomes
sex chromosomes
what are multi factorial disorders?
congenital malformations
cancers
coronary artery disease
what are chromosomes or cytogenic disorders?
nondijunction in mieosis that causes a missing chromosomes (monosomics) or an extra chromsome (trisomics)
down syndrome
XYY syndrome