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Biology 1406 Exam 4
J. Pickard's Summer Biol 1406
36
Biology
Undergraduate 1
07/01/2016

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Term
What happens in binary fission? What type of cells divide this way?
Definition
a. Bacteria divide by asexual binary fission
i.Single, circular bacterial chromosome is replicated, cell pinches in two
Term
Chromosomes
Definition
i. Composed of chromatin
1.DNA and protein
Term
Chromatin
Definition
i. A complex of nucleic acids (e.g. DNA or RNA) and proteins (histones)
ii. Condenses to form a chromosome during cell division
Term
Nucleosome
Definition
i. Complex of DNA and histone proteins
ii. Promote and guide coiling of DNA
Term
Define a karyotype.
Definition
a. Array of chromosomes in an individual organism
Term
Diploid
Definition
i. 2 complete sets of chromosomes
ii. 46 total chromosomes in humans
Term
Haploid
Definition
i. 1 set of chromosomes
ii. 23 in humans
Term
Describe homologous chromosomes.
Definition
a. One from mother, one from father
Term
What happens to each chromosome prior to replication?
Definition
a. Prior to replication, each chromosome composed of a single DNA molecule
Term
Sister chromatids
Definition
i. One chromosome composed of 2 sister chromatids
Term
Centromere
Definition
i. Join sister chromatids
Term
Cohesin Protein
Definition
i. A protein complex that regulates the separation of sister chromatids during cell division
1. Either mitosis or meiosis
Term
What are the 3 subphases of interphase? What happens in each?
Definition
a. G1
i.Growth
b. S
i. Replicate DNA
c.G2
i.Ready for mitosis
Term
Kinetochore
Definition
i. Attachment site for microtubules
Term
Mitotic Spindle
Definition
i. The mitotic spindle is the macromolecular machine that segregates chromosomes to two daughter cells during mitosis
Term
Centrosome
Definition
i. Organelle that is the main place where cell microtubules get organized
ii. They occur only in plant and animal cells
Term
Aster
Definition
i. Radial array of microtubules in animals (not plants)
Term
What happens in prophase? Which organisms have centrioles?
Definition
a. Chromosomes condense and become visible
b. 2 centrioles move to opposite poles forming spindle apparatus (no centrioles in plants)
c. Nuclear envelope breaks down
Term
What happens during prometaphase?
Definition
a. Sister chromatids attach to microtubules at kinetochores
b. Oriented to opposite poles
c. Move to equator
Term
Describe metaphase.
Definition
a. Alignment of chromosomes along metaphase plate
Term
Describe metaphase.
Definition
a. Alignment of chromosomes along metaphase plate
Term
What happens in anaphase?
Definition
a. Centromeres split
b. Cohesin proteins removed
c. Sister chromatids pulled to opposite poles
Term
What is the end result of telophase?
Definition
a. Spindle apparatus disassembles
b. Nuclear envelope reforms around each set of chromosomes
c. Chromosomes decondense
d. Nucleolus reappears
Term
Compare animal and plant cytokinesis.
Definition
i. Animal cells
1. Actin filaments produces a cleavage furrow
ii. Plant cells
1. Cell plate forms between the nuclei
Term
Cytokinesis
Definition
i. Division of cytoplasm
Term
What regulates the eukaryotic cell cycle?
Definition
a. Checkpoints
Term
What is the relationship between checkpoints and the cell cycle control system?
Definition
a. Cell cycle can be put on hold at specific points called checkpoints
i. Process is checked for accuracy and can be halted if there are errors
ii. Allows cell to respond to internal and external signals
Term
Describe growth factors?
Definition
a. Act by triggering intracellular signaling systems
b. Can override cellular controls that otherwise inhibit cell division
Term
Cancer
Definition
i. Unrestrained, uncontrolled growth of cells
1. Failure of cell cycle control
Term
Describe the significance of meiosis and the sexual life cycle.
Definition
a. Sexual reproduction is able to generate genetic variation in offspring because the process of meiosis randomly shuffles genes across chromosomes and then randomly separates half of those chromosomes into each gamete
b. The two gametes then randomly fuse to form a new organism
c. Genetic variation is one of the keys to evolutionary fitness
Term
Meiosis
Definition
i. Cell division to produce haploid sperm and egg
Term
Fertilization
Definition
i. Union of haploid sperm and haploid egg to form diploid zygote
Term
Synapsis
Definition
i. During early prophase I
ii. Homologous chromosomes become closely associated
iii. Includes formation of synaptonemal complexes (tetrads)
Term
What is the end result of Meiosis I?
Definition
a. Results in daughter cells that contain one homologue from each chromosome pair
Term
What is the end result of Meiosis II?
Definition
a. Four new haploid gametes
Term
Is there an interphase prior to meiosis?
Definition
a. Meiotic cells have an interphase period that is similar to mitosis with G1, S, and G2 phases
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