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
what are sex chromosome disorders?
klinefelter syndrome causes sterility and female body characters in males
turner syndrome causes sterility and immature sex organs in females
XXX syndrome causes learning difficulties
XYY syndrome causes behavioural difficulties
what is a single gene disorder?
a mutant gene - can be recessive (both parents carry) or dominant (one parent carries)
cystic fibrosis
huntington’s
duchenne muscular dystrophy
sickle-cell anemia
what did Miescher do?
isolated new molecule called nuclei (DNA)
what did Griffith do?
tried to make vaccines and discovered that cells can transform
what did Oswald do?
repeated Griffith’s experiment and discovered that nucleic acids were what transformed in the cell
what did Hershey and Chase do?
used radioactive phases to show that DNA = genes (theoretical basis)
what did Franklin do?
used X-ray crystallography differaction to show the structure of DNA
what did Watson and Crick do?
used Farnklin’s pictures to make a DNA model
what did Meselson and Stahl do?
proved that DNA replicates semi-conservatively
what did Kornberg do?
showed that DNA replication only moved from 5’ to 3’ and is initiated from a double stranded segment
what is the structure of DNA?
nucleotide building blocks made of nitrogenous base (A,G,C,T)(3’ end) deoxyribose (5’ end) and a phosphate, and are joined together by phospodiester bonds
what are purines?
adenosine and guanine
what are pyrimadines?
cytosine, thymine, uracil
what does helicase do?
unwinds double helix of DNA
what does SSBIs do?
temporarily binds to separated DNA to keep it stable
what does RNA primase do?
synthesizes RNA primer
what does DNA polymerase III do?
synthesis DNA nucleotides next to RNA primer nucleotides
what does DNA ligase do?
smooths over strands and joins Okazaki fragments
what is the lagging vs leading strand?
lagging stand runs 3’ to 5’ so needs to be made discontinuously via Okasaki fragments
what is transcription?
when DNA is converted into mRNA by RNA polymerase reading codons
what are the three types of RNA?
mRNA (messenger) carries info needed to make proteins
tRNA (transfer) transports amino acids to ribosomes (during protein synthesis)
rRNA (ribosomal) complex with proteins to make ribosomes
what is translation?
converting RNA to proteins using ribosomes, tRNA, and genetic codes (codons and anticodons)
what are regularly genes?
genes that code for regularity allosteric proteins, which change after binding with a ligand to decrease/increase affinity for DNA (they have active and regulatory sites)
what is the lac oberon?
regularly gene that controls lactose production
what is the tryptophan oberon
regulatory gene that is repressed by tryptophan
what are the types of mutations?
-chromosomal translocation
-transposition of genes
-point mutations
what are the types of nucleotide pair substitution mutations?
silent (doesn’t change anything)
missense (changes one codon/amino acid)
nonsense (results in a stop codon)
what are the types of nucleotide pair insertion or deletion mutations?
frameshift (immediate nonsense)
frameshift (extensive missense)
three nucleotide pair insertion of deletion
what are the repair enzymes?
nuclease
DNA polymerase
DNA ligase
what does p53 protein/gene p21 do?
halts cell cycle to allow DNA repair
activates DNA repair genes or other needed genes
can activate apoptosis if needed
what are restriction enzymes?
make recombinant DNA by cutting DNA into fragments based on the sequence, leaving “sticky ends” that can be used to join two different DNA sequences that were cut by the same restriction enzyme
what is gel electrophoresis?
separates DNA molecules based on size by puting them into gel and move towards positively charged electrode and the shorter molecules move faster
what is PCR?
polymerase chain reaction - uses taq polymerase (heat stable) to replicate DNA
how could you clone DNA?
amplify DNA using PCR
cut target DNA and cloning plasmid (small circular DNA) with restriction enzymes
mix and ligate target fragment
select for bacteria harbouring your gene
what is transgenic tech?
introduction of genetic information into the zygote of an animal (pro nuclear injection)
what are gene knockouts?
controls the number of copies in a specific locus (gene targeting)
