unit 2

DNA: The molecule that carries genetic info for the development and function of organisms. Stands for deoxyribonucleic acid

Chromosome: a subunit (or molecule) of DNA in nucleus of a cell. When in their condensed form they look like “I” in many organisms

Duplicated Chromosome: Two connected subunits (or molecules) of DNA in nucleus of a cell that are duplicates of each other that will separate during cell division often looks like an “X”

Chromosome Pairs: Two unconnected subunits of DNA that contain the same genes but are not copies of each other, so there are some differences. One is inherited from each parent looks like “I I”

Diploid: an indivudal with two versions (i.e., pairs) of each chromosome

Nucleotides: “The four nucleotides in DNA — Adenine (A), Cytosine (C), Guanine (G) and Thymine (T) — are small molecules that collectively compose a sequence in DNA molecules

Gene: a gene is a segment of DNA on a chromosome that provides info for making molecules like mRNA and proteins

  • genes are information - they don’t “do” or “make” anything

Allele: A version of a gene that is different (based on nucleotide sequence) from another version of the same gene. Most genes have more than one allele.

Homozygous: a diploid individual with the same alleles for a given gene

Heterozygous: a diploid individual with different alleles for a given gene or nucleotide position

Chromosome copies: two connected subunits of DNA that are copies of each other

  • same genes, same info in genes

  • DNA sequences are identical

  • copies seperate during cell division

  • looks like an X

Chromosome pairs: two unconnected subunits of DNA that contain the same genes but are not copies of each other

  • differences occur, because one chromosome in the pair is inherited from each parent

Chromosome Copies

  • No (few) differences

  • duplicates

  • connected

  • looks like “X”

  • inherited from one parent

Both

  • two molecules

  • same genes

  • located in the nucleus of a cell

Chromosome Pairs

  • multiple differences

  • unduplicated

  • unconnected

  • looks like “I I”

  • each chromosome inherits from a different parent


Genotype

  • number of instances of sequences CAG in the DNA sequence of a gene

Phenotype

  • involuntary movements in a patient with a neurologic disorder

  • number of instances of a certain amino acid in a protein

  • age of onset of disease in a patient

  • mental state (ex: depression) of patients

  • volume (cubic cm) of patients


Coding vs. Noncoding

Every single gene has a coding and noncoding region

Coding region is responsible for coding a protein, information that is transcribed into an mRNA molecule, which is translated, each set of three nucleotides of the mRNA molecule encodes a specific amino acid. The ribosome brings over one amino acid at a time and assembles the amino acid chain

Noncoding DNA provides information on how much to encode (amount)

Coding and Noncoding DNA affects the phenotype

Huntington Disease, sheep wool, explained by coding DNA variation

Corn-branching and lactose tolerant cases, explained by noncoding DNA

Noncoding DNA

influences how much transcription happens, more transcription means more mRNA influences which cells a gene is transcribed in

when (under what conditions) the gene is transcribed

How do gene regulatory switches work?

certain segments of the gene, are the gene regulatory switches