GENETIC-CONCEPTS

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GENETIC-CONCEPTS
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1. Genome
2. Chromosome
3. Gene
4. DNA/RNA
5. Nucleic Acid
6. Protein
7. Amino Acid

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Genome

• Entirely of an organisms heredity information
• Complete set of instructions for making an
  organism
• All of the hereditary information encoded in an
  organisms DNA.
• Master blueprints for all enzymes, cellular
  structures activities
• An organisms complete set of DNA
• All the DNA contained in the cell of an organism
• The collection of DNA that comprises an organism

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Prokaryotic Organism

• Eubacteria and Archaea. Usually unicellular.
• No internal membrane-bound compartments DNA
  floats free in the cytoplasm.
• 1 circular chromosome (plus optional plasmids,
  which are also circular)
• reproduction usually asexual
• sexual processes (mixing DNA from 2 individuals)
  occur, but with unequal contributions from the 2
  partners
• transcription and translation simultaneous

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Prokaryotic genomes

• Most have a single, double-stranded circular DNA
  molecule
• Usually without introns
• Since there is no nucleus, the DNA floats freely
  within the cell
• Proteins cause the DNA to coil tightly forming a
  nucleoid region
• Relatively high gene density
• Often indigenous plasmids are present

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Eukaryotic Organism

• Plants, animals, fungi, protistas. Often
  multicellular.
• DNA contained within a membrane-bound nucleus.
• linear chromosomes (usually more than 1)
• careful division of chromosomes in cell division
  mitosis and meiosis
• transcription separated from translation
• sexual reproduction 2 partners contribute
  equally to offspring
• life cycle alternation of haploid and diploid
  phases (i.e. 1 vs. 2 copies of each gene and
  chromosome)

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Eukaryotic genomes

• Genetic information is divided in the chromosome.
• The size of genomes is species dependent
• The difference in the size of genome is mainly
  due to a different number of identical sequence
  of various size arranged in sequence
• The gene for ribosomal RNAs occur as repetitive
  sequence and together with the genes for some
  transfer RNAs in several thousand of copies
• Structural genes are present in only a few
  copies, sometimes just single copy. Structural
  genes encoding for structurally and functionally
  related proteins often form a gene family
• The DNA in the genome is replicated during the
  interphase of mitosis

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Eukaryotic Genome
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Chromosome

• A DNA histone protein thread, usually
  associated with RNA, occurring in the nucleus of
  a cell
• Chromosomes contain hundreds of genes encoded
  within their DNA

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Chromosome Logical Structure

• Locus
• Location of a gene/marker on the chromosome.
• Allele
• One variant form of a gene/marker at a
  particular locus.

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Gene

• The material that controls which traits are
  expressed in an organism
• Genes come in pairs and offspring inherit one
  copy of each gene from each parent
• A section of DNA that codes for a trait
• Material of heredity

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Heredity

• The passing of traits from parent to offspring

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Allele
The different forms of a trait that a gene may
have. One form of a gene
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Traits

• Ways of looking, thinking, or being.
• Traits that are genetic are passed down through
  the genes from parents to offspring

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Recessive

• A trait that is covered over, or dominated, by
  another form of that trait and seems to disappear
  
• Hidden when the other copy of the gene contains
  the dominant allele.
• A recessive allele shows up only when there is no
  dominant allele present
• Shown with a lower-case letter (a)

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Dominant

• A trait that covers over, or dominates, another
  form of that trait
• Trait that always shows up, even when only one of
  the two alleles is in the dominant form
• Shown by a capital letter (A)

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Homozygous

• Both alleles forms of the gene are the same
• When offspring inherit two dominant genes, (one
  dominant gene from each parent) they are said to
  be homozygous dominant (AA)
• When offspring inherit two recessive genes, (one
  recessive gene from each parent) they are said to
  be homozygous recessive (aa)

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Heterozygous

• When alleles occur in different forms
• When offspring inherit one dominant gene and one
  recessive gene, they are said to be heterozygous
  (Aa)
• Since the dominant gene will be expressed, they
  are said to be heterozygous dominant (Aa)

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Genotype

• An organism's genetic makeup

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Genotype
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PHENOTYPE

• Outward physical appearance and behavior of an
  organism

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PHENOTYPE
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Genes
Segment of DNA which can be transcribed and
translated to amino acid
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Central Dogma of Biology

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DNA, RNA, and the Flow of Information
Replication
Translation
Transcription
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Central Dogma (Modifications)
(2)Ribozymes
Transcription
Translation
Protein
DNA
RNA

• Reverse
• transcription

Replication
(2)Self Replication
(3)Self Replication
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DNA as Genetic Material

• DNA encodes all the information in the cell
• The composition of the DNA is the same in all
  cells within an organism
• Variation among different cells is achieved by
  reading the DNA differently
• DNA contains four bases that encode all the
  information to make an organisms life

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RIBO NUCLEIC ACID

• A polymer composed of nucleotides that contain
  the sugar ribose and one of the four bases
  cytosine, adenine, guanine and uracile
• Polynucleotide containing ribose sugar and
  uracile instead of thymine
• Primary agent for transferring information from
  the genome to the protein synthetic machinery

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Types of RNA

• Three types of RNA
• messenger RNA (mRNA)
• transfer RNA (tRNA)
• ribosome RNA (rRNA)
• Remember
• All produced in the nucleus

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Codon

• There are 20 different possible amino acids to
  make from different codons
• Amino acids
• the building of protein
• 3 possible stop codon
• 1 start codon
• TAC on DNA
• AUG on RNA

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Gene Expression

• Production of proteins requires two steps
• Transcription involves an enzyme (RNA polymerase)
  making an RNA copy of part of one DNA strand.
• There are four main classes of RNA
• i. Messenger RNAs (mRNA), which specify the amino
  acid sequence of a protein by using codons of the
  genetic code.
• ii. Transfer RNAs (tRNA).
• iii. Ribosomal RNAs (rRNA).
• Translation converts the information in mRNA into
  the amino acid sequence of a protein using
  ribosomes, large complexes of rRNAs and proteins.

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Steps of gene expression

• Transcription DNA is read to make a mRNA in the
  nucleus of cells
• Translation Reading the mRNA to make a protein
  in the cytoplasm

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Poly-peptide

• A primary structure of a protein
• A sequence of amino acid bonded together by
  peptide bonds.

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Protein

• A polymer of amino acids which may consists of
  one or more polypeptide chains
• Protein may be water insoluble and serve a
  structural role or be water soluble with
  catalytic activity