Mendelian and molecular genetics Flashcards
what was the important question did Aristotle attempt to answer?
what is the essence of a chicken???
what is formal cause?
the structure, essence or pattern that gives a thing its identity
what was the blending theory of inheritance
the outdated theory that offspring inherit traits as a simple mix of their parents traits.
who was Gregor Mendel?
an Austrian monk credited as the father of genetics. he proposed a ‘particle’ theory of inheritance.
why are peas a good model for studying genetics?
controlled process
lots of offspring
short generation times
how was Mendel able to control genetic crosses in his experiment?
by studying strong traits.
what is true-breeding?
an organism continues to produce the same trait when cross fertilized with itself over many generations.
what is P-generation, f1-generation and F2-generation?
P-generation= parent generation
F1-generation= 1st generation
F2-generation= 1st generation crossed with itself.
what is Mendel’s Law of Segregation?
-an organism possesses two factors (alleles) for each trait.
-during gamete formation these factors segregate, such that a gamete possesses one factor for each trait.
-Fertilization restores the presence of two factors for each trait in the offspring
– Some factors are ‘dominant’ and mask the effect of ‘recessive’ factors
what does genotype mean
refers to the combination to the combination of factors (types of genes)
what does phenotype mean?
the type of trait as a result of genotype. ex. tall, short etc.
what does dominant and recessive refer to?
recessive and dominant alleles.
what is a dihybrid cross?
a genetic breeding experiment where two organisms with two different traits are crossed.
what is Mendel’s law of independent assortment
during gamete formation the factors of one trait segregate independently of factors for another trait.
how was Mendels work rediscovered?
William Bateson saw de Vries’s publication while completing a paper on ‘Problems of Heredity’ ; then searched out the copy of Mendel’s report in Cambridge University Library.
what did Thomas Morgan do?
used fruit flies in his experiments to demonstrate that genes are located on chromosomes, establishing the theory of heredity.
who coined the term ‘gene’ ?
Wilhelm Johannsen
what important functions must DNA perform?
DNA must copy itself with great fidelity and encode genetic information.
why were scientists interested in the structure of DNA?
understanding the structure of DNA allows for the understanding of how genetic information is copied, encoded and passed down through generations. this also allows for a deeper understanding of evolution.
what speculation did Schrodinger make about the structure of DNA?
“aperiodic crystal.” he stated that hereditary material is likely to be a molecule which unlike a crystal does not repeat itself, implying its nature allows for an infinite number of combinations with a small number of atoms.
how did Watson and Crick discover the structure of DNA
with the x-ray image made by Rosalind Franklin, known as photo 51.
what was Rosalind franklins contribution?
she was able to crystalize DNA and x-ray it to photograph DNA.
what is the structure of DNA
a double helix nucleotide with 4 nitrogenous bases, Thymine (T) Adenine(A) Cytosine (C) Guanine (G)
what are nucleotides?
phosphate sugars with hydrogen bonds connecting them to nitrogenous bases.
what is complementary base pairing?
the specific pairing of nitrogenous bases (a and t or g and c)
which bases are complementary to each other?
A and T, G and C
how many hydrogen bonds form between each nitrogenous base?
3 H bonds
what is meant by anti-parallel?
each strand in DNA is parallel but moving it opposite directions. one builds up while another builds down.
how are the 5’ and 3’ ends distinguished.
by numbering the carbons on the bases, with carbon 1’ being closest to the base and carbon 5’ closest to the phosphate.
what is the width and electrical charge of a DNA molecule?
2nm long. DNA is very negatively charged due to the phosphate and base groups, this negative charge allows it to be separated through gel electrophoresis.
what does the Helicase do?
Helicase is an enzyme that the DNA strand feeds into to split into 2.
what is a replication fork?
a replication fork is the shape DNA makes when its fed into the Helicase and splits in two, making a forked shape.
what does primase do?
an enzyme that creates short RNA sequences called primers, which are essential for DNA replication.
what does DNA polymerase do?
Polymerase goes on two one of the branches of the replication fork and copies and makes a new strand of DNA.
how does replication differ between the leading and lagging strand?
the leading strand synthesized continuously in the same direction as the replication forks movement, the lagging strand synthesizes in the opposite direction of the fork in fragments (Okazaki fragments)
what are Okazaki fragments?
Okazaki fragments are the clumps of synthesized DNA on the lagging strands.
what does ligase do?
it binds the Okazaki fragments together on the lagging strand.
what is the central dogma of genetics?
the central dogma is the idea that genetic information flows only in one direction. DNA→(transcription)RNA→(translation)protein.
how do DNA and RNA differ?
DNA is double stranded with the bases A T C G.
RNA is single stranded with the bases A U C G.
what is transcription?
transcription is the process of the RNA polymerase attaches to the promoter (START) making an RNA copy of DNA. this copy is messenger RNA (mRNA)
what is translation?
translation is the process of decoding mRNA into amino acids during protein synthesis.
what are the stages of transcription?
initiation, elongation, termination
what occurs during initiation?
RNA polymerase binds to the promoter region.
what occurs during elongation?
during elongation the polymerase moves along the DNA producing a RNA strand.
what is messenger RNA (mRNA)?
mRNA is a single stranded RNA that comes from DNA synthesis.
what are promoter and terminator sequences?
the promoter is the START codon and the terminator sequence is the STOP codon.
what role is served by the ribosomes?
the ribosome reads the mRNA and translates the genetic code into amino acids.
what are codons?
groups of three mRNA nucleotides that encode a specific amino acid.
what is transfer RNA (tRNA)
tRNA is a small molecule that serves as a link between the mRNA and the amino chain.
how does DNA in eukaryotic and prokaryotic DNA differ.
prokaryotic: double stranded, circular, single chromosomes.
eukaryotic: double stranded, linear, multiple chromosomes.
what are the differences between genotype and phenotype.
genotypes represent genomes and while phenotypes describe them.
what did Craig Venter do?
helped sequence the human genome and created the first artificial genome.
what is an operon?
A functional genetic unit consisting of genes
and regulatory sequences that control the
expression of one or more genes.
who discovered operons?
Jacques Mond
how do inducible and repressible operons differ?
inducible operons can be turned on in the presence of a small molecule, repressible operons are on by default and are turned off by small molecules.
What are repressor proteins?
A protein that binds to DNA (operon) to turn off gene expression.
