Genetics Exam 3

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Extranuclear Inheritance

Extranuclear Inheritance

Genetic information is transmitted to progeny through the cytoplasm, not the nuclear genes. Exhibits nonMendelian inheritance patterns.

maternal effect, infectious heredity, organelle heredity

3 forms of extranuclear inheritance

maternal effect

Results from the egg containing the stored products of the nuclear genes of the female parent

Organelle heredity

Results from the expression of DNA contained in the mitochondria or chloroplasts

infectious heredity

Results from the symbiotic or parasitic association of microorganisms with eukaryotic cells

the ovum

Where does the majority of the cytoplasm in a zygote come from?

MZT

Stage where development comes under exclusive control of zygotic genome

maternal genotype

In traits determined before the zygotic genome becomes active, the maternal effect states that what will determine the progeny's phenotype?

embryonic polarity

In drosophila, what do maternal effect genes determine?

bicoid (bcd)

-Specifies anterior development -Mother must have one wild type allele for functional anterior development

maternal ooplasm

In infectious heredity viruses or other microorganisms existing in a symbiotic relationship can be passed through the __________ to the progeny.

yes

will (nos-/ nos-) mothers produce embryos that lack abdominal structures, even if the embryos have a functional nos allele?

chloroplasts and mitochondria

what organelles contain DNA?

mother, child

Traits defined by the organellar genome exhibit a ______ to _____ inheritance pattern

Carl Correns

-Discovered variation in four o clock plants -Found inheritance determined by which plant provided the egg, genetic info contained in chloroplast or cytoplasm influencing it

Mary B. and Hershel K. Mitchell

-Discovered slow growing strain of Neospora -Phenotype of strain contributing cytoplasm determined progeny phenotype

prokaryotes

studies of chloroplast and mitochondria revealed that they more closely resembled ________ than eukaryotes

circular dna that lacks histone proteins, ribosome type

In what way does chloroplast and mitochondrial DNA resemble prokaryotes?

Lynn Margulis

Proposed embosymbiotic theory

2 billion, engulfed

Endosymbiotic theory states that: Mitochondria and chloroplasts arose about ______ years ago as free-living protobacteria that were _______ by larger, primitive eukaryotic cells

chloroplast DNA

-Multiple copies within 1 -100 to 225 kb -Includes long noncoding sequences

Mitochondrial DNA

-Multiple copies in 1 -Smaller and more variable in size than cpDNA -Very little noncoding DNA

mitochondrial function

-particularly vulnerable to mutations in the DNA -due to very little noncoding DNA, and most genes are transcribed from a single promoter

Heteroplasmy

-The presence of mixture of normal and mutant organelles in a common cytoplasm -Can dilute impact of mutant mitochondria

amitotic

There is variability in phenotype among progeny and between parents and progeny because organelles are distributed to daughter cells in this fashion.

Maternal inheritance pattern, a specific mutation in one of the mitochondrial genes, deficiency in bioenergetic function

What must be true for a human genetic disorder to be attributed to mitochondria?

Mitochondrial replacement therapy

Treatment used to attempt to stop the passing of a mitochondrial genetic disorder to child

Walter Sutton and Theodor Boveri

Proposed the chromosome theory of heredity

Friedrich Miescher

First described DNA in 1868

Phoebus Levene

Proposed DNA was composed of a repeating chain of tetranucleotides, with nucleotides found in a 1:1:1:1 ratio

proteins

What was believed to be the genetic material before DNA

Frederick Griffith

-Studied Streptococcus pneumoniae -called conversion of R cells to S cells transformation

Oswald Avery, Colin M. MacLeod, and McLean McCarty

-Identified the “transforming principle” by eliminating one molecule at a time from the extract of heat-killed S cells and testing for transformation -showed that DNA was the “transforming principle”

Nucleases

Enzymes that break phosphodiester bonds in RNA and/or DNA

Protease

Breaks peptide bonds in polypeptides

Hershey and Chase

-Blender experiment studied bacteriophage T2 which infects ecoli -Infected ecoli w/ radioactive phage and centrifuged

• Showed DNA entered ecoli DNA, not protein to conclude DNA is hereditary material

Nucleotides

-basic building block of nucleic acids -Each consists of a phosphate, a pentose (a 5 C sugar) and a different nitrogenous base

ribose and deoxyribose

What are the types of pentose sugars?

smaller, cytosine, thymine, uracil

Is a pyrimidine the smaller or bigger nitrogenous base type and what are the pyrimidines?

bigger, adenine, guanine

Is a purine the smaller or bigger nitrogenous base type and what are the purines?

Nucleoside

-A base covalently linked to a sugar -Joined by a N-glycosidic linkage

1' C of sugar links to N 1 or 9 of base

what is a N-glycosidic linkage?

nucleotide

-A nucleoside covalently linked to a phosphate -Joined by a phosphoester linkage

ester linkage

link between an acid and an alcohol

phosphates

One way to name nucleotides is by the name of nucleotide plus the number of _______.

5,3, phosphodiester

In polynucleotides, nucleotides are joined by ’-to-’ __________ bonds

phosphate, -OH

Polynucleotides always create free _______ at 5’ end and free ________ at 3’ end

2 nm

Electron microscopy during the 1940s showed that DNA was a long thread-like molecule with a diameter of what?

10^-10 m

1 Å (Angstrom) = ?

store and encode genetic info, express genetic info, replicate faithfully, be capable of mutation, have stability

What are the requirements of the hereditary molecule?

Erwin Chargaff

Measured the base composition of DNA from various species

purines, pyrimadines, T=A, G=C

Chargaffs rules state that the total amount of =, so __= ___ and __ = __

Rosalind Franklind

Used X-ray diffraction to determine the structure of DNA, showed that DNA was a helical molecule composed of more than one polynucleotide chain with the bases stacked on top of each other and with a 0.34 nm distance between the bases.

Watson and Crick

Described the structure of DNA to the scientific community, awarded nobel prize

right handed double helix

What did watson and crick propose the structure of dna was?

clockwise

In a right handed helix, two helices wind around each other in a ______ fashion

sugar-phosphates

What is on the outside of the helix

antiparallel

The two polynucleotide chains are _________

central axis

What are the bases oriented towards?

non-polar covalent bonds

how are bases held together in DNA

hydrogen bonds between the bases

How are the 2 DNA helices held together?

3, 2

How many H-bonds between G-C? Between A-T?

10

Typically, how many base pairs are there per turn of the helix?

Central Dogma (Crick)

Explains flow of genetic info fromDNA to RNA to protein

B DNA

Form of DNA described by Watson and Crick

A DNA

-Characteristic of RNA/DNA hybrids -shorter/broader

Z DNA

-Synthetic DNA consisting of GC base pairs -Left handed helix -long/thin

ribose, uracil not thymine, single stranded

Typical differences in RNA from DNA are...

Svedberg Coefficient

-A measure of how quickly particles move through a substance when subjected to centrifugation -Related to molecular weight, but not directly

Spectroscopy

Characterizes molecules by the way that they interact with various wavelengths of light

ultraviolet, 260

What type of light does DNA absorb and at what wavelenght is maximum absorption?

denaturation

-The separation of the two polynucleotide chains in a DNA molecule -Accomplished by breaking H-bonds through the addition of acids, bases, or alcohols or by the removal of stabilizing counterions or by heat

Hyperchromic shift

Increase in UV absorption w/ increasing temperature

melting temperature

-The temperature at which one-half of the DNA is no longer double-stranded

G and C beacuse they have 3 H-bonds between

The presence of more of which bases increase Tm and why?

cooled quickly

If a solution of denatured DNA is ________ it will remain denatured

Held at a temp a few degrees below Tm

If the solution is ____________ , the native ds DNA can re-form

annealing

-reassociation of single stranded DNA to double stranded DNA -Occurs by incubating just below melting temp

hybridization

Annealing of single stranded DNA from two different sources

FISH

-Single stranded fluorescently labeled DNA is hybridized to a sequence of interest

semi-conservative

What fashion did Watson and Crick propose DNA replicates in?

John Cairns

-stated that semi-conservative replication would require a replication fork -Experimented w/ ecoli in autoradiograms to show this -Bacterial DNA replicates in a circle

origin of replication (ori)

What is the point that replication is initiated called?

1

How many ori in a prokaryote?