PRACTICE SET WITH SOLUTIONS A+
◉ Life Cycle of the Cell. Answer: G1-G0-G1-S-G2-Mitosis
◉ G1. Answer: Interphase growth period within the cell
◉ G0. Answer: Interphase rest period
◉ S. Answer: Interphase period of DNA replication, contents of
chromosomes double
◉ G2. Answer: Second phase of interphase growth
◉ Molecular Structure of DNA. Answer: DNA, also called
Deoxyribose nucleic acid, is an anti-parallel double helix composed
of nucleotides.
Each nucleotide contains a phosphate group, a 5 carbon sugar group,
and a nitrogen base (A,G,C,T)
,Nucleotides are attached together to form two long strands that
spiral to create a structure called a double helix. If you think of the
double helix structure as a ladder, the phosphate and sugar
molecules would be the sides, held together by phosphodiester
bonds, while the bases would be the rungs. The bases on one strand
pair with the bases on another strand: A pairs with T, and G pairs
with C, forming the DNA molecule.
A and T are held together by 2 hydrogen bonds while G and C are
held together by 3
◉ Molecular Structure of RNA. Answer: The structure of RNA is
made up of three components, one of which is a five-carbon sugar
called ribose sugar. One of the carbons of the ribose sugar is
attached to a nitrogenous base, which is A,G,C, or U. Another of the
carbons of the ribose sugar is attached to the phosphate group. Yet
another carbon is attached to a hydroxyl group.
What makes RNA different from DNA is that it uses Uracil instead of
Thymine and it has an OH group on the 2' carbon instead of the plain
H that DNA has.
◉ Deoxyribose sugar of DNA compared to Ribose sugar of RNA.
Answer: http://www.mun.ca/biology/scarr/iGen3_02-07_Figure-
L.jpg
,◉ Mitosis. Answer: The devision of a mother and daughter cell into
genetically identical cells. Prophase-Prometaphase-Metaphase-
Anaphase-Telophase
◉ Prophase. Answer: Chromosomes are condensed
◉ Prometaphase. Answer: Nuclear envelope dissolves
◉ Meselson and Stahl. Answer: Meselson and Stahl's experiment
tested which model of DNA, i.e., the conservative, semi-conservative,
and dispersive models, was correct.
They grew Ecoli in N^15. They then took the N^15 and put it into
N^14 medium and allowed DNA replication to take place. They took
samples, spliced them, spun them in a centrifuge, and viewed which
layers emerged because N^15 was heavier than N^14. They saw that
there wasn't just a band for N^15 and N^14, but a half dark, half
light band. This threw the conservative model out. After the second
generation went by there was an equal distribution of half light and
half dark bands.
The Semi-Conservative model of DNA was supported by this.
, ◉ Conservative Model. Answer: Every time a new molecule of DNA is
produced it is completely brand new (brand new molecule)
◉ Semi-conservative Model. Answer: Each strand of DNA becomes
integrated with a new strand into a new double helix (half old
molecule and half new)
◉ Dispersive Model. Answer: Both original strands of DNA become
interspersed throughout the new model (unequal proportions of
new DNA to old DNA)
◉ Metaphase. Answer: Chromosomes align along the middle of the
cell
◉ Chargaff's Rules. Answer: A and T are always in the same
abundance.
G and C are always in the same abundance.
Different species have different %AT vs %GC
◉ Anaphase. Answer: Chromosomes are pulled apart, pulling two
identical daughter chromosomes to each end of the cell