Genetic Material Flashcards
Relationship b/w DNA, genes, chromosomes
genes –> DNA –> chromosomes
- chromosomes contain multiple genes, and so are able to code for multiple proteins; and since each chromosome is made of a single DNA strand then the same is said for DNA
each gene is made of a DNA sequence
What are chromosomes (include stuff about condensation)?
- threadlike single DNA strand/mlc wraps around histones to form nucleosomes that condense into chromatin
- chromatin is normally decondesned (so no visible chromosomes) when the cells is NOT undergoing division
- chromatin is going to tightly condense into distinct chromosomes to prep for cell division, so that chromosomes are equally split b/w the nuclei.
- a SINGLE DNA mlc.
What are genes?
- each gene contains a DNA sequence
- the mlcr unit of heredity (passed on from parent to offspring)
gene variant = alleles
What do genes code for?
proteins
genetic code is PERMANENTLY STORED in DNA
What is the diploid and haploid status of human cells
- diploid (2n) = 46 chromosomes - 1 copy from mom and 1 copy from dad of the 23 unique chromosomes
- haploid (1n) = 23 chromosomes - 23 homologous pairs/ 23 unique chromosomes
DNA
* what is the monomer
* what are 2 other major characteristics of DNA?
- monomer: nucleotides [ phosphate + pentose sugar + nitrogenous base]
- double helix + anti-parallel
DNA vs RNA (what are the 3 key differences?)
- pentose sugar in nucleotide (deoxyribose in DNA and ribose in RNA)
- nitrogenous base in nucleotide (Thymine in DNA and Uracil in RNA but still pairs with adenine)
- helix status (double in DNA and single in RNA)- but RNA is rarely found in single strand form bc complementary parts within the single strand fold back on itself
What is the base pairing rules? How many bonds (and what type of bonds) are b/w the base pairs?
- A pairs with T (apples on trees) (T is U in RNA) - 2 H bonds
- C pairs with G (cars need gas) - 3 H bonds
What are the purines? What are the pyrimidines? How many rings for each group?
- purines (2 rings)- AGgies (adenine and guanine) are PURe
- pyrimidine (1 ring) - C and T
What is the backbone of DNA? What bonds the backbone together?
- phosphate group + pentose sugar
- phosphodiester bond, which is covalent
Describe the sense strand
- aka coding strand
- runs from 5’ to 3’ direction
- strand used in translation and the result of/ exact sequence after DNA replication and transcription
Describe the anti-sense strand
- aka TEMPLATE strand, complementary strand
- runs in 3’ to 5’ direction
- used as template strand for DNA replication and DNA transcription so able to add on nucleotides in the 5’ to 3’ direction
In what direction are nucleotides ALWAYS being added?
5’ to 3’ direction
Explain DNA replication
- DNA helicase unzip and unwind the 2 DNA strands at the origin of replication (breaking the H- bonds) in both directions [ topoisomerase is preventing the supercoiling upstream of helicases]
- RNA polymerase (aka DNA primase) adds on RNA primer in 5’ to 3’ direction on both DNA strands
- DNA polymerase adding DNA nucleotides in 5’ to 3’ direction after the RNA primer (continuously for the leading strand)
- lagging strand: multiple RNA polymerases and DNA polymerases adding nucleotides in 5’ to 3’ direction but whole strand moving in the opposite direction (3’ to 5’)
- DNA polymerase changes the RNA primer into DNA nucleotides
- DNA ligase seals the fragments (of okazaki fragments and leading and lagging strands)
Explain transcription
DNA –> RNA (mRNA, tRNA, rRNA)
- RNA polymerase attaches to the template DNA strand {3’ to 5’ strand} promoter region to unzip DNA
- RNA polymerase adds RNA nucleotides (T sub for U) in the 5’ to 3’ direction to make PRE-MRNA
- pre-mRNA undergoes splicing of interfering introns and splice together exons as well as alternative splicing
- final mRNA exits through the nuclear pores of nuclear envelope to be translated in cytoplasm