Molecular Genetics

What does DNA stand for

Deoxyribonucleic acid.

What does the nucleus of every cell contain?

DNA.

What makes DNA special?

It can replicate itself thus allows for cell division.

What does DNA do?

Provides directions that guides the direction/function of cells, repair of worn cell parts and the construction of new cells and cell parts.

Responsibility of DNA?

Direct the cell to produce needed proteins.

What do different sequences of DNA do?

Genes direct the ribosomes to produce different proteins.

Where does protein synthesis occur?

In the ribosomes.

What does RNA stand for?

Ribonucleic acid.

RNA role in protein synthesis.

Transfer the info from the nucleus to the cytoplasm and eventually to the ribosome.

Gene

Segment of DNA that directs bodily structures or functions.

Structural genes

Control traits through production of proteins.

Erwin Chargaff 1950

Analyzed base pairs of DNA which are common to all living things. Created the pairing rules.

Who analyzed the base pairs of DNA and created the pairing rules.

Erwin Chargaff.

Rosalind Franklin and Maurice Wilkins 1951

Used X-ray diffraction to show the structure of DNA. Showed the double helical model with phosphate groups on the outside and the base pairs inside.

Who used X-ray diffraction to show the structure of DNA?

Rosalind Franklin and Maurice Wilkins.

1953 James Watson and Francis Crick

Built a model of the structure of DNA which matched the x-ray diffraction data from Franklin and Wilkins.

Who determined the structure of DNA by building a model?

James watson and Francis Crick.

1963 Nobel Prize

Franklin, Watson and Crick for their work on the discovery of the structure of DNA.

Where is Genetic Information found?

Genetic info is concentrated in the nucleus of a cell.

Chromosomes

Large storage containers of genetic information.

Somatic cells

Body cells.

How many chromosomes does the Human somatic cell have?

46 chromosomes.

Gametic cells

Sex cells.

How many chromosomes does the human gamete cell have?

23 chromosomes.

Which chromosome determines sex?

23rd chromosome.

Karyogram

Picture/diagram of the chromosomes of a cell, arranged in homologous pairs in a numbered sequence.

What factors identify homologous chromosomes.

similar size, length and the same gene in the same place just different versions.

Which chromosome pairs are homologous?

Chromosomes 1-22.

Karyotyping

Process; extract chromosomes from cell and match them up.

What are chromosomes made up of?

Long strands of DNA that are further separated into several genes along the strands length.

Locus/loci

Location

Genes and location

Each gene occupies a certain locus on a certain chromosome.

Human Genome

Mapping of loci of all human genes along the 46 chromosomes.

Old School Cassette analogy, the cassette is a large bundle of tape (____), containing many tracks (___) this is similar to a?

DNA, Gene, Chromosome.

One song or track on a cassette is like a?

Gene.

The tape in a cassette is used to record info like?

DNA.

Different versions of the same song are like?

Alleles.

Alleles

Different version of the same gene.

Cc

C and c are the same gene. C is the dominant allele and c is the recessive allele.

How was the human genome project an international effort?

Involved 18 countries who set up human genome research programs for genetics from 1990-2003.

Human Genome Project

Determined what genes went on what chromosomes and what those genes do.

What does the closeness of genes mean in gene mapping?

The closer the genes the more likely the genes are to appear together.

Human Genome Timeline 1950s

Watson and Crick made a model of the DNA molecule and proved that genes determine heredity.

Human Genome Timeline 1990s

Dolly the sheep; the first adult animal clone.

Human Genome Timeline 2000s

J. Craig Ventor and Francis Collins announce the sequencing of the entire human genome.

Human Genome Timeline 2003

Final completion of the human genome.

Human genome TImeline 2008

Pres. Bush signed legislation to prevent loss of jobs and health insurance when genetic testing reveals that the person is susceptible to costly disease.

What is the first benefit to having a database (HGP) for research?

Knowledge of gene expression and proteomics in normal and diseased individuals.

Proteomics

Protein’s function.

What is the second benefit to having a database (HGP) for research?

Diagnosis of genetic disorders by identifying causal genes.

What is the third benefit to having a database (HGP) for research?

Enhancement of medications that target specific genes.

What is the fourth benefit to having a database (HGP) for research?

Evolution and population diversity studies through gene comparison.

Genes and the Human Genome

Humans have variations of these genes (personal genome) the order and sequence of these genes is alike within a species (the human genome).

Eukaryotic chromosomes

Have a membrane bound nucleus and membrane bound organelles.

What holds DNA in place within a chromosome.

Proteins.

What are Chromosomes composed of? (GENERAL)

DNA and proteins.

What are the 2 forms of chromosomes?

Single stranded and double stranded chromosomes.

Single Stranded Chromosomes

Made up of one molecule of DNA.

Double Stranded Chromosomes

Made up of two molecules of DNA.

Centromere

Protein that holds chromosome together.

When would there be a double stranded chromosome?

During cell division.

Is a single strand of DNA considered one chromosome? A double strand?

Yes and Yes.

What happens to the chromosome during the cell’s division cycle?

Chromosome goes from single stranded to double stranded.

Why are chromosomes double stranded during cell division?

So there are 2 copies of DNA in preparation for each cell to receive a copy.

what are the 2 DNA strands called in Double stranded DNA? What other important component is there?

Sister Chromatids. Centromere which holds them together.

Chromatid

One of the two identical halves of a chromosome that has been replicated for cell division.

Sister Chromatids

Two chromatids which are identical to each other and are attached by the centromere.

Are sister chromatids the same as homologous chromosomes?

No. Sister chromatids are exact replicas, homologous chromosomes are not.

What happens to DNA when cell division is not occuring?

Double and single stranded DNA will remain in chromatin form until cell division.

Chromatin

Stretched DNA which is inter-tangled in the nucleus.

What happens to Chromatin during cell division?

The genetic information condenses and takes the form of chromosomes.

Chromatin form and Chromosome form

99% of the cell’s life DNA is in the form of chromatin.

Prokaryotic chromosomes Characteristics

Unicellular, no nucleus, DNA is loose/free flowing.

Prokaryotic chromosomes

Have only one essential chromosome that contains all genes to regulate life processes.

Circular DNA

AKA nucleoid DNA. The one chromosome of prokaryotic cells is in the form of a loop.

Plasmids

Extra loops or rings of DNA. Some prokaryotes have them.

Eukaryotic groups

Animalia, Fungi, Plantae and protista.

Prokaryotic groups

Archaea and Eubacteria.

Telomere

Ends of the chromosome which prevent it from unwinding and fraying.

DNA structure composition general

Two strands of nucleotides bonded together to form a polynucleotide. The two strands are antiparallel.

Antiparallel

Left-hand strand runs in the opposite direction of the right-hand strand.

Nucleotide

Monomer of nucleic acid.

Why is the order of base pairs important?

The order dictates what proteins are made.

How can you find the 5’ end?

Look for the phosphate at the end.

How can you find the 3’ end?

Look for the hydroxide at the end.

What are the 3 parts of the nucleotide? (DNA)

1. Sugar (deoxyribose).

2. Phosphate.

3. Nitrogen Base (G, C, A, or T).

What are the 3 parts of the nucleotide? (RNA)

1. Sugar (Ribose).

2. Phosphate.

3. Nitrogenous base (G, C, A, or U).

DNA parts in orientation

Each strand has a sugar phosphate backbone which the nitrogenous bases stick out of towards the center.

What holds the DNA strands together?

Hydrogen bonds between the bases.

What holds the nucleotides together?

Phosphodiester bonds.

Phosphodiester bonds

Covalent bonds.

WHat shape do the two strands of DNA form?

Double Helix.

Double Helix

Twisted ladder shaped. Twisted clockwise.

How is DNA a twisted ladder?

The opposing base pairs form the rungs and the sugar phosphate backbone form the struts (sides).

What are the 4 nitrogenous bases in DNA?

Guanine, Cytosine, Adenine and Thymine.

Pyrimidines

Nitrogenous bases that are single-ringed.

What are the Pyrimidines of DNA

Cytosine and Thymine.

Purines

Nitrogenous bases that are double ringed.

What are the purines of DNA?

Adenine and Guanine.

What is the pairing rule General?

Pyrimidine always bonds with a purine.