Chapter 6 Flashcards
(22 cards)
What are Genes
coding regions of DNA that contain instructions for making proteins responsible for each inherited trait
What is DNA Packaging
Enormous amount of information stored in DNA must fit inside the nucleus of each cell!
What is The Genome
-Entire set of DNA of an organism
-Eukaryotic genome, often diploid, occurs in pairs of homologous chromosomes
How many Genomes do humans have
Humans have 23 homologous pairs of chromosomes of different sizes, two of which are sex chromosomes
Who was Meischer
-studied the composition of the nucleus
-extracted an “unknown substance” Called it “nuclein” b/c he found it in the nucleus of WBC
Who was Griffith
-accidently shed light on the function of DNA in inheritance
Who were Avery, McLeod & McCarty
found out that DNA was the “transforming” substance
Who was D. Hershey & Chase
Concluded… Radioactivity was ONLY detected in cells infected by viruses with phosphorus radioisotope. DNA must be responsible for carrying genetic info.
Who was
4 nitrogenous bases had been identified:
A and G – double-ringed purines
T and C – single-ringed pyrimidines
Who was Chargaff
- discovered that the bases occur in definite ratios where A = T and C = G known as “Chargaff’s Ratios”
-was a chemist
Who was Franklin & Wilkins
building models of DNA to determine it’s structure
What is a complementary strand
two parent strands separate and a new complementary strand is built for each
What unbinds DNA
Unwinds DNA by breaking apart H-bonds b /w base pairs
What is the replication fork
As the 2 strands separate, they form a Y-shaped structure
What direction are new strands built in
5’ to 3’ direction
What are Okazaki fragments
the small fragments that the lagging strand is made of
What is the leading strand
the strand in the 3’ to 5’
what is the lagging strand
the strand in the 5’ to 3’ direction
DNA is wrapped around how many histones and nucleosomes
8 histones
48 nucleosomes
what are plasmids
Smaller pieces of DNA, called plasmids, float throughout the cell
What are Telomeres and what do they do
Repetitive and non-coding sequences of DNA at the end of a chromosome
Protects coding regions (important parts of DNA) from being lost during replication
