Genetics Chapter 9, 10, 11

Special information pathways (transfer within the cell)

1) Reverse transcription = and some viruses, information is transferred from RNA to DNA 2) RNA replication = or to another RNA molecule

Chromatin Has a highly complex structure with several levels of organization

1) at the simplest level, chromatin is a double stranded helical structure of DNA 2) DNA is complexed with histones to form nucleosomes 3) each nucleosome consists of eight histone proteins around which the DNA wraps 1.65 times 4) The nucleosome's fold up to produce a 30 nm fiber 5) that forms loops averaging 300 nm in length 6) The 300 nm loops are compressed and folder to produce a 250 nm wide fiber 7) tight coiling of the 250 nm fiber produces the chromatids of a chromosome

The structure of DNA can be considered at three hierarchical levels

1) the primary structure of DNA is it's nucleotide sequence 2) The secondary structure is a double stranded helix 3) The tertiary structure is the higher order folding that allows DNA to be packed into the confined space of a cell

Major Information Pathways (transfer within the cell)

1) transcription = information is transferred from DNA to an RNA molecule 2) DNA replication = Information is transferred from one DNA molecule to another 3) translation = information is transferred from RNA to a pro team through a code that specifies the amino acid sequence

genetic material possesses several key characteristics

1. Genetic material must contain complex information 2. Genetic material must replicate faithfully 3. Genetic material must encode the phenotype 4. Genetic material must have the capacity to vary

Chloroplast shown to have their own DNA in what year?

1963

Human cells contain more than how many base pairs of DNA

6 Billion base pairs and would measure over 2 million (over 6 feet) stretched end to end

Nucleotide

A building block of DNA, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and a phosphate group.

virulent phage

A phage that reproduces only by a lytic cycle. Always kills the host

Virus

A piece of code that is capable of copying itself and typically has a detrimental effect, such as corrupting the system or destroying data

Bacteriophage

A virus that infects bacteria

Kossel was known for the discovery of __________

A, C, T, G. (Four nitrogenous bases)

acetyltransferase

An enzyme that covalently links acetate groups to substrates, such as amino acid side chains of proteins.

transductants

Bacterial genes can be moved from one bacterial strain to another producing recombinant, bacteria

Transduction

Bacterial virus is take DNA from one bacterium to another

Transduction

Bacterial virus is, bacterial phage, carry DNA from one bacterium to another, transduction usually occurs between bacteria the same are closely related species

Transformation

Bacterium takes up DNA from the medium, recombination takes place between introduce jeans in the Backtrail chromosome

Transformation

Bacterium takes up three DNA from the surrounding

cotransformed cells

Cells that are transformed by two or more genes

F prime cells

Contains F plasmid carrying some bacterial genes

Which part of the phage (it's DNA or protein) serves as the genetic material and is transmitted to phage progeny?

DNA IS THE GENETIC MATERIAL IN BACTERIOPHAGES

moderately repetitive DNA

DNA consisting of sequences that are from 150 to 300 bp in length and are repeated thousands of times.

Avery, MacLeod, McCarty

DNA is the genetic material because degradation of DNA led to a cessation of bacterial transformation

negative supercoiling

DNA is underroatated so right-handed (NEGATIVE) supercoil compensates

H-DNA

DNA structure consisting of three nucleotide strands (triplex DNA). Can occur when a single nucleotide strand from one part of the molecule pairs with double-stranded DNA from another part of the molecule Often occurs in long sequence of only purines or only pyrimides

highly repetitive DNA

DNA that consists of short sequences that are present in hundreds of thousands to millions of copies; clustered in certain regions of chromosomes.

Conjugation

Direct transfer of DNA from one bacterium to another with no reciprocal exchange of genetic material

Miescher

Discovered nuclein/ performed first chemical analysis of DNA

F'

Donor. Present As separate circular plasmid, caring some bacterial jeans

T2 is a bacteriophage that infects what?

E.coli

Topoisomerase

Enzymes that add or remove rotations from the DNA helix by temporarily breaking the nucleotide strands, Rotating the ends around each other, and then re-joining the broken ends

Two basic types of chromatins

Euchromatin and heterochromatin

Watson and Crick

Figured out structure of DNA was a double helix

Nucleosome

IS THE FUNDAMENTAL REPEATING UNIT OF CHROMATIN The core of proteins and DNA produced by digestion with nucleus enzymes as a simplest level of chromatin structure, DNA wrapped around 2 times around an October's of 8 histone proteins (2 copies each of H2A, H2B, H3, and H4)

Chromosome fragments that lack centromeres are lost where?

In mitosis

Denaturation

In proteins, a process in which a protein unravels and loses its native conformation, thereby becoming biologically inactive. In DNA, the separation of the two strands of the double helix.

F (fertility) factor of E. Coli

Is an episode that controls mating and gene exchange between E.Coli cells

Leber hereditary optic neuropathy

Mitochondrial disorder creates a defective enzyme responsible for converting oxygen, fats, and simple sugars to energy. Characterized by vision loss.

Acetylation

Process that alters chromatin structure

endosymbiotic theory

Proposes that mitochondria and chloroplasts were once free living bacteria that became internal inhabitants of early eukaryotic cells, it's assume that over evolutionary time many of the endosymbiosis original genes were subsequently lost (because nuclear genes existed that provided the same function) or a transferred to the nucleus

In eukaryotes, DNA in the cell is closely associated with ?

Proteins called Histones This complex of DNA and proteins is called chromatin

RNA Viruses: Retroviruses

RNA virus that has been Intergrated into the host genome.

F-

Recipient and is absent

renaturation

Regaining the correct tertiary structure after denaturation of a protein. If single stranded DNA is slightly cooled The hydrogen bonds will form again between complementary base pairs

Heterochromatin

Remains in a highly condensed state throughout the cell cycle, even during interphase, more condensed, located at centromers, telomers and other specific places, repeated sequences, few genes replicated at the late S phase, transcription is in frequency and crossing over is uncommon

B-DNA

Right-handed helical structure of DNA that exists when water is abundant; the secondary structure described by Watson and Crick and probably the most common DNA structure in cells.

interspersed repeats

Scattered throughout the genome

Satellite DNA

Short sequences of DNA that are tandemly repeated as many as 10 million times in the DNA; much of it is located in the telomeres

Bacterial chromosomes are

Small circular molecules called plasmids which replicate independently of the chromosomes

Plasmids

Small rings of DNA found naturally in some bacterial cells in addition to the main bacterial chromosome. Can contain genes for antibiotic resistance, or other "contingency" functions. Also used extensively in genetic engineering

Movement of genetic information between nuclear mitochondrial and chloroplast genomes

Some sequence is normally found in the mitochondrial DNA have been detected in nuclear DNA, Chloroplast to mitochondria nuclear to mitochondrial

reverse transcriptase

Synthesizing DNA from RNA or DNA template HIV causes AIDS

DNA at the ends of Eukaryotic chromosomes consists of what?

Telomeric sequences

melting temperature (Tm)

The temperature at which DNA denatures

secondary structure of DNA

Two anti-parallel strands twist into a double helix, stabilized by hydrogen bonding between complementary bases (A-T & G-C) and hydrophobic interactions.

Euchromatin

Undergoes the normal process of condensation Andy condensation in the cell cycle On chromosome arms, unique sequence, many genes, replicated throughout S phase, common crossing over and transcription often

Telomere structure

Usually consists of repeated units of a series of adenine or thiamine nucleotides followed by several guanine nucleotides, taking the form 5" to 3" end (A or T)magnificent-3", where m ranges from 1 to 4 and n is 2 or more.

Chargaff's Rule

[A]=[T] and [G]=[C], they pair up across from one another forming two strands also called base pairing.

Hfr cell

a cell with the F plasmid integrated into the chromosome High frequency donor

Shelterin

a multiprotein complex that binds to telomeres and protects the ends of the DNA from being inadvertently repaired as a double-stranded break in the DNA

temperate phage

a phage that is capable of replicating by either a lytic or lysogenic cycle Phage DNA integrates into bacterial chromosome where it remains as in active prophage

merozygote (partial diploid)

a strain of bacteria containing F' factor genes

Griffith's experiment

an experiment carried out by Griffith using the heat-killed bacteria in mice to discover that a factor in heat-killed, disease-causing bacteria can "transform" harmless bacteria into ones that can cause disease

competent cells

are able to take up naked DNA, occur naturally AND can be created in the laboratory.

Gene transfer in bacteria

conjugation, transformation, transduction

unique-sequence DNA

consists of sequences that are present only once or, at most, a few times in the genome

centromere structure

constricted region of a chromosome where spindle fibers attach

tandem repeats

copies of genes repeated one after another along a chromosome Intend to be clustered a particular locations on the chromosome

cytoplasmic inheritance

cytoplasmic genes, which are usually inherited entirely from only one parent

Hershey-Chase Experiment

determined that DNA is the genetic material

DNase

digests DNA

F+ cell

donor cell, present at separate circular plasmids

Tobacco Mosaic Virus

first virus discovered by Wendell Stanley and found that genetic information was carried in RNA

Methylation and phosphorylation

for our purposes think closing DNA

promiscuous DNA

genetic material can be exchanged between nucleus, chloroplasts and mitochondria

polytene chromosomes

giant chromosomes Are found in certain tissues of drawers so drosophila larvae and some other organs These large, unusual chromosomes arise when repeated rounds of DNA replication take place without accompanying cell divisions, Producing thousands of copies of DNA that lie side-by-side

hairpin structure

in single strands of nucleotides, when sequences of nucleotides on the same strand are inverted complements, a hairpin structure will be formed RNA molecule's may contain numerous hairpins allowing them to fold up into complex structures

positive supercoiling

molecules that are overrotated exhibits positive supercoiling

horizontal gene transfer

mtDNA transfer From one Plant to another

Episomes

plasmids that can integrate into the genome

Primary structure of DNA

sequence of deoxyribosenucleotides; bases include adenine, thymine, cytosine, and guanine

Epigenetics

the study of changes in organisms caused by modification of gene expression rather than alteration of the genetic code itself.

Supercoiling

twisting in the opposite direction to the turns of the double helix during the first stage of mitosis. (Overwinding or underwinding of DNA leads to supercoils)

constitutive heterochromatin

usually located near centromeres and telomeres