Lecture 16 Flashcards
Heredity?
The passing on of physical or mental characteristics genetically from one generation to another
Where is our genetic information stored?
In the nucleus as DNA
Genotype?
- Genetic constitution of the cell
- A set of traits
Phenotype?
Phenotype = genotype + environment
- The physical expression of the genotype (what you see )
How many chromosomes do humans have?
22 identical pairs of chromosomes (autosomes)
1 pair of sex chromosomes (allosomes)
What does increasing the packing of DNA decrease?
Decreases gene expression due to reduced accessibility
When is DNA most active?
- In an uncondensed form
- Gene expression
When is DNA most unactive?
- In an condensed form
- No gene expression
- e.g chromosome
What does a DNA helix wrap around to condense itself?
Histone proteins
Information flow?
DNA-Transcription-mRNA-Translation-Polypeptide
Genome?
Library of genes
Purines?
- Adenine and guanine
- Double ring
Pyrimidines?
- Thymine and cytosine
- Single ring
What is DNA?
A polymer that consists of nucleotides (bases = a,t,g,c)
What is each DNA strand made up of?
- Base
- Sugar
- Phosphate
Composition of the DNA helix?
- Two polynucleotide strands are wound together about a common axis (anti parallel orientation)
- A sugar-phosphate backbone on the exterior of the helix
- Purine and pyrimidine nucleotide bases are on the interior of the helix
What are the two grooves that that twisting strands of DNA have?
- Major groove
- Minor groove (sugar-phosphate backbone runs closer together here)
How many hydrogen bonds hold a and t together?
2
How many hydrogen bonds hold g and c together?
- 3
- Requires more energy to break cytosine and guanine apart
What is the direction of a DNA strand?
5 prime to 3 prime
What does 5 prime and 3 prime mean?
Describes the two main positions of carbon that are involved in the synthesis of DNA
What is the direction of that DNA is transcribed from?
5 prime to 3 prime
When does DNA replication happen?
During s-phase of interphase
What type of process is DNA replication?
A semiconservative process where a parental strand (template) is used to create a new complementary daughter strand
