Cell Cycle Test Flashcards
What are the two main stages in the cell cycle?
Interphase and mitosis
What are the phases in interphase?
Gp 1, Synthesis, Gap 2
What happens in Gap 1
cell grows in size
duplicates organelles
cell’s “birthday”
What happens at the Gap 1 checkpoint?
checks if enough nutrients are present
checks for damaged DNA
What happens in the S phase?
centrosomes duplicate
DNA duplicate
What happens in the Gap 2 phase?
cell grows in size
cell prepares to divide
What happens at the G0 checkpoint?
cell is not duplicating its DNA
cell is not dividing
What are the stages of mitosis?
Prophase, Metaphase, Anaphase, Telophase
What happens in prophase?
mitotic spindle forms
nuclear envelope breaks down
chromosomes start to form
What happens in prometaphase (late prophase)?
growing spindle
centrosomes at poles
nuclear envelope broken down
What happens in metaphase?
centrioles at poles
sister chromatids at the metaphase plate
What happens in anaphase?
chromosomes pulled to poles
microtubules (spindle fibers) push apart
chromatids pulled apart
What happens in telophase?
spindle breaks down
nuclear envelope reforms
chromosomes decondense (into chromatin)
What is a nucleotide made of
phosphate group, 5-carbon sugar, nitrogen base
What is the difference between purines and pyrimidines?
Purines: 2 rings
Pyrimidines: 1 ring
What nitrogenous bases are purines?
Adenine and Guanine
What nitrogenous bases are pyrimidines?
Thymine and Cytosine
What are the four nitrogenous bases?
Adenine, Thymine, Guanine, Cytosine
What bonds hold the 2 DNA strands together?
hydrogen bonds
What are the backbones of the strands made of?
phosphate-sugar backbones
DNA runs -
5’ - 3’ (5 prime to 3 prime)
*the 5 prime is the nitrogenous base with the phosphate group on top (see images in Notes+)
DNA is ___
Antiparallel
(One strand runs 5’ to 3’, while the other runs 3’ to 5’. This means that one is upside down…basically)
DNA Replication begins at the ____
Origin of replication
Which cells have multiple origins of replication?
Eukaryotic cells
What is the benefit of having multiple origins of replication?
It makes DNA duplication faster
What occurs at the replication fork?
DNA replication
DNA replication takes place in ___ directions
Both
DNA replication take place moving ____
Away from the origin of replication
Replication forks are created at
the origin of replication
How do replication bubbles form
When the replication forks move apart
What happens when the replication bubbles connect with other bubbles that have formed around other origins of replications
they collide and 2 new strands of DNA are made
Topoisomerase role
unwinds DNA
Helicase role
Breaks the hydrogen bonds (which separates the nitrogenous bases)
SSB role
keep the 2 strands separated
DNA polymerase role
Adds new nucleotides to DNA strand being created
How does DNA polymerase know what nucleotide to add next?
It reads the bases on the original and adds the complementary bases
DNA polymerase can only add new bases ____ to a strand of DNA. What does this result in?
5’ to 3’; this results in one being made continuously and another made in fragments
continuously-made strand called
Leading strand
Strand made in small segments called
Lagging strand
Lagging strand segments called
Okazaki fragments
Okazaki Fragments are joined together by
DNA ligase
What does DNA ligase do to glue the fragments together?
it forms a covalent bond between deoxyribose sugar and a phosphate group of another
DNA primase role
adds an RNA primer that lets DNA polymerase know where to add new nucleotides
