Chapter 4,12, and 15 review for exam Flashcards
four types of bases in DNA
Adenine
thymine
guanine
cytosine
four types of bases in RNA
Adenine
Uracil
guanine
cytosine
what does the backbone of DNA and RNA consist of?
phosphate group
nitrogenous base
five carbon sugar
how does DNA become proteins
DNA ——> RNA——> Proteins
transcription turns DNA into RNA
translation turns RNA into proteins
What nitrogenous bases are pyrimidines
cytosine
uracil or thymine
what nitrogenous bases are purines
guanine
adinine
(both guanine and adenine have the word “nine” in the word which links them to purines)
what is the bond that holds two nucleotides together
phosphodiester linkage
Characteristics of polymerization
- requires energy
- non spontaneous reactions
- ATP is an activated nucleotide
What is the difference between DNA and RNA structure?
DNA structure:
- has thymine in it
- double stranded and double helix
- very stable and not as flexible
- carries more information because it is more stable
RNA structure:
- hydroxyl group (making it more reactive)
- has uracil in it
- single stranded
- more bendable and flexible
- can be a ribozyme that can act as a catalyst
What are the complementary base pairs of both DNA and RNA
DNA
- A and T (two hydrogen bonds)
- G and C (Three hydrogen bonds)
RNA
- A and U (two hydrogen bonds)
- G and C (Three hydrogen bonds)
DNA Structure:
primary: sequence of deoxyribonucleotides; bases are A T G and C
secondary: two antiparallel strands twisted into a double helix, stabilized by hydrogen bonding, hydrophobic interactions, and van der waals interactions
tertiary: double helical DNA forms compact structures by wrapping around histone proteins or twisting into supercoils.
DNA Synthesis occurs in which direction
five prime to three prime direction
RNA Structure:
Primary: sequences of ribonucleotides; bases are A U G and C
Secondary: most commonly a single strand that folds back on itself to form a double helical “stem” and unpaired “loop”
Tertiary: Secondary structures fold to form a wide variety of distinctive three dimensional shape
what does semi conservative mean regarding DNA synthesis?
each new double stranded DNA molecule consists of one of the original strands from the parent molecule in order to conserve the original DNA in each copy
What are the enzymes that are involved in DNA Synthesis
- DNA Helicase
- Topoisomerase
- Primare (RNA polymerase)
- DNA polymerase I
- DNA polymerase III
- Ligase
What does Ligase do?
enzyme that puts the two strands of DNA together
- carries out the reaction to form a phosphodiester linkage at the end
what does DNA helicase do?
breaks the bonds between nitrogenous bases and unzips the double helix so the DNA can be replicated
function of topoisomerase
cutting, shuffling, and religating DNa strands
function of primase (RNA polymerase
synthesis of RNA primer
function of DNA polymerase III
responsible for synthesizing new DNA strands during DNA replication
function of DNA polymerase I
to remove RNA primers from the newly synthesized DNa strand during replication and fill in the gaps left behind by the primers with the needed DNA nucleotides in the lagging strand
Is DNA Synthesis exergonic or endergonic
dna synthesis is endergonic
where is DNA found in eukaryotic cells?
in the nucleus
where is dna found in prokaryotic molecules?
in the nucleoid
do plasmids contain DNA?
yes, plasmids do contain some DNA
How many chromosomes do humans have?
23
what bases are at the beginning of replication and why?
adenine and thymine are because they only have two hydrogen bonds that helicase has to break through making it easier to start replication.
what is the function of single strand DNa binding proteins?
attach two separate strands to prevent them from closing
which direction is the lagging strand synthesized
synthesized away from the replication fork
where does DNA synthesis occur?
in the nucleus
what are the three main functions of cell division
reproduction, growth and development, and tissue renewal
how do cells replicate?
- copying DNA (s phase)
- separating copies (mitosis)
- dividing cytoplasm to create two complete cells (cytokinesis)
is mitosis sexual or asexual reproduction?
asexual
what does interphase consist of?
G1, s phase, and G2
what occurs during G1
cell growth, RNA/protein synthesis,. accumulates nutrients to go through mitosis later
what occurs in S phase
DNA replication and dna repair
what occurs in G2
dna synthesis is complete, microtubules are also complete
what phases occur in mitosis
prophase
prometaphase
metaphase
anaphase
telophase
what happens in prophase
chromosomes condense, spindle apparatus begins to form
what happens in prometaphase
nuclear envelope breaks down, microtubules connect to chromosomes at kinetochores
what happens in metaphase
chromosomes complete migration to the middle of the cell
what happens in anaphase
sister chromatids separate into daughter chromosomes which are pulled to opposite poles of the spindle apparatus
what happens in telophase
nuclear envelope reforms and chromosomes condense
what occurs in cytokinesis
- cell division begins: actin - myosin ring causes plasma membrane to begin pinching in
- cell division is complete: two daughter cells have formed
- cleavage furrow: visible indentation that forms on the surface of animal cells during cytokinesis
define chromosome
a structure containing genetic information in gene form
define chromatin
the material that makes up eukaryotic chromosomes; consists of a DNA molecule and histone proteins
define sister chromatids
tow attached double stranded DNA copies of a replicated chromosome. when chromosomes are replicated, they consist of two genetically identical chromatids; when they separate, they become individual chromosomes
define centromeres
regions of chromosomes where sister chromatids are joined
define kinetochores
structure on a sister chromatid where microtubules attach
define dentrosome
microtubule organizing center in animals and certain plants/fungi; each pole in the spindle apparatus is a centrosome
what are the checkpoints in the cell cycle
G1 checkpoint: cells pass if nutrients are sufficient, growth factors are present, cell size is adequate, and DNA is undamaged
G2 Checkpoint: cells pass if chromosome replication is successfully completed, no DNA damage, and activated MPF is present
(MPF: mitosis promoting factor)
Metaphase checkpoint: pass if all chromosomes are attached to the spindle
