Exam 2 Flashcards
Define characters
Observable physical features
List an example of a character
Flower color, seed shape
Define traits
Forms of a character
List examples of traits
Purple flowers, wrinkled seeds
In what organisms are cell division and reproduction the same
Single-celled organisms
What is the difference between an asexual and a sexual life cycle?
An asexual life cycle has asexual cell division, meaning offspring are identical to each other and the parent. A sexual life cycle has meiosis and fertilization, so offspring differ from one another and their parents.
What is the difference between a diplontic and a haplontic life cycle?
In a diplontic life cycle, the mature organism is diploid and the gametes are the only haploid stage. In a haplontic life cycle, the mature organism is haploid and the zygote is the only diploid.
What event occurs during G1?
prepare for cell division
What event occurs during S?
DNA Replication
What event occurs during G2?
preparation for mitosis
What event occurs during M?
mitosis and cytokinesis
What event occurs at prophase?
Prophase: centrosomes divide (if present), chromosomes condense, spindle starts to form
What event occurs at prometaphase?
Prometaphase: nuclear envelope breaks down, chromosomes attach to fully formed spindle
What event occurs at metaphase?
Metaphase: alignment of replicated chromosomes on the metaphase plate.
What event occurs at anaphase?
Anaphase: centromere division and movement of sister chromatids to opposite poles.
What event occurs at telophase?
Telophase: decondensing of chromosomes and re-formation of nuclear membranes.
How does binary fission differ from the mitotic cell cycle?
The main difference is the co-occurrence of DNA replication and segregation in binary fission. Binary fission in prokaryotes does not use a microtubule spindle.
Define aneuploidy
A condition in which the number of one or more chromosomes is either lacking or in excess.
Define necrosis
occurs in multicellular organisms when a cell is damaged or is starved of nutrients, oxygen, or water.
Necrotic cells often swell up and burst, releasing their contents into the extracellular environment. This process often results in inflammation, which also affects surrounding tissues. When a multicellular individual dies, all of its cells will soon succumb to this kind of death.
What difference between plants and animals best explains why they undergo cytokinesis in different ways?
The rigid cell wall of a plant cannot be deformed by a contractile ring
How does cytokinesis begin in animal cells?
furrowing of the cell membrane
Define contractile ring
the contractile ring generates the constricting force to separate one cell into two cells.
Telophase
In meiosis, DNA replicates____the nucleus divides
one less time than
Which of the following is most likely to lead to aneuploidy?
Nondisjunction
In the haplontic life cycle, the mature organism is haploid and the _______ is the only diploid stage
Zygote
Which statement about plant cytokinesis is true?
Vesicles fuse to form a cell plate
Define centrosomes
?
Define chiasmata
An X-shaped connection between paired homologous chromosomes in prophase I of meiosis. A chiasma is the visible manifestation of crossing over between homologous chromosomes.
A monosomic individual has 27 chromosomes. What is the haploid chromosome number?
14
Caspases play a role in the process of
apoptosis
With respect to what happens with the nuclear envelope, telophase is most like the opposite of
prometaphase
When a cell, or organism, has an unequal number of copies of each chromosome, it is
aneuploid
Maternal chromosome 1, paternal chromosome 2, and maternal chromosome 3 go to the same pole during meiosis. This is an example of
independent assortment
Hayflick limit
The maximum number of cell divisions for a normal (human) cell before apoptosis occurs (due to telomere shortening).
The ori region is the site where which of the following starts?
DNA Replication
A key event controlling the transition from one cell cycle phase to the next is the synthesis and subsequent breakdown of a particular
Cyclin
DNA replication and segregation co-occur in
binary fission
If greater than normal amounts of the G1/S cyclin-CDK were produced, the most likely result would be ______
of RB and ______of the cell cycle.
more phosphorylation; acceleration
What action do CDKs perform on target proteins?
they add a phosphate group to the protein
Cells that do not divide usually arrest during
G1
What is the essential difference between necrosis and apoptosis?
In apoptosis, cell death is part of the normal developmental process; in necrosis, cell death is the result of something going wrong.
Mitosis/Meiosis?:Homologous chromosomes come together and line up along their entire lengths
only in meiosis
