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What determines variation within species?
- -Different forms (alleles) exist for the different genes
- -species have their own specific set of alleles
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genotype is...
The set of alleles that an individual possesses
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What are phenotypes?
Alleles that individually represent messages for specific proteins that generate expressible traits
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What is a genome?
The complete set of DNA possessed by an individual
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Eukaryotes contain most of their DNA in the form of...
chromosomes found in their nuclei, but they also contain DNA in mitochondria and chloroplasts (plants).
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Nucleotides are...
monomers bound together into long polymers
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Nucleotides consist of...
a five carbon sugar (deoxyribose), a phosphate and a nitrogenous base.
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Four different bases are in DNA:
Adenine (A), Guanine (G), Cytosine (C), and Thymine (T). The first two are purines, the latter two are pyrimidines. Uracil (U) replaces Thymine in RNA and is a pyrimidine also.
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the 5' carbon is where the ____ attaches and the 1' carbon is where the ____ attaches.
- Phosphate
- nitrogenous base
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A sugar phosphate backbone is....
generated by phosphodiester bonds forming between the phosphate of one nucleotide and the 3' carbon belonging to the sugar of an adjacent nucleotide.
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The two sugar phosphate backbones assume an ______ orientation.
Anti-parallel
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A _____ is a region of DNA capable of being transcribed to produce a functional RNA molecule at the correct time and in the correct place.
Gene
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A _______ must be associated with each gene allowing it to be activated.
Regulatory region
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At the other end of the gene there must be a _____.
termination signal
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Most eukaryotic genes contain______that must be excised from the RNA prior to rejoining the______and forming a functional message.
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Genome types:
- Plasmid
- Organellar
- Virus
- Prokaryotic
- Eukaryotic Nuclear
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Plasmid Genome are...
- typically circularized DNA found in bacteria, apart from the primary bacterial DNA.
- Usually have genes and an origin for replication.
- Multiple copies per cell is common.
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Organellar genome are...
- DNA in mitochondria and chloroplasts.
- Several copies are typical per organelle.
- DNA is usually in a circular configuration.
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Virus Genome are...
- a protein coat surrounds the genomic core.
- The genome can consist of single or double stranded RNA or DNA depending on viral type.
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Prokaryotic Genome are...
- Usually a single, closed, circular DNA.
- Functionally related genes are often adjacent to each other forming groups called operons that are turned on or off simultaneously.
- The DNA is concentrated in the nucleiod, which is not membrane bound.
- Non-histone proteins are associated with the DNA for packing it.
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Eukaryotic Nuclear genome are...
- One continuous double stranded DNA molecule together with associated histone and non-histone proteins forms an individual chromosome.
- A single set of all the different types of chromosomes in an organism is referred to as the haploid genome.
- Species typically have a specific number of sets of chromosomes (their ploidy). Those with one set are haploid, two diploid, three triploid, etc.
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A karyotype is a...
- picture of all of the chromosomes of an organism arranged in homologous pairs according to decreasing size.
- These arrangements are facilitated by the location of the centromeres of the chromosomes.
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The centromere is a...
contracted region of the chromosome necessary for attachment of microtubules during Mitosis and Meiosis.
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Chromosome ends are referred to as _____.
telomeres.
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Bands may appear when Chromosomes are stained following chemical treatment. Depending on the procedure these bands may reflect regions of high compaction (_____) or low compaction (____).
- heterochromatin
- euchromatin
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Two other physical landmarks that exist are nucleolar organizing regions(NOR) and chromomeres.
- The NOR is the portion of the DNA where the message for rRNA resides and ribosomes are assembled in the surrounding volume Fig 2-16.
- Chromomeres are beadlike thickenings that appear along the DNA early during nuclear division.
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In eukaryotes, DNA has associated with it histone proteins that organize it into _____.
- Nucleosomes are octamers of 4 types of histones (H2A, H2B, H3, and H4).
- DNA wraps around this octamer 2 times (like thread on a spool) producing the nucleosome that is 10nm in diameter.
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