Mitosis and Meiosis Test Expectations+ Flashcards
Define: Haploid
The term used to describe a single set of chromosomes that equals half the diploid count. In humans, haploid count equals 23.
Define: Diploid
The term used to describe a complete set of chromosomes, consisting of one from each parent. Humans have a diploid count of 46.
Define: Chromosome
The means of storage for DNA in a cell or organism. Every species has a distinct number,
Define: Sister chromatid
A pair of identical chromosomes, derived from the division of a single chromosome, that align at a common centromere
Define: Centromere
(Greek, CENTR-, “center”) The central point at which a pair of sister chromatid attach to one another
Define: Tetrad
(Greek, TETRA-, “four”) A group of four chromatids formed by pairs of homologous chromosomes
Define: Tetrad
(Greek, TETRA-, “four”) A group of four chromatids formed by pairs of homologous chromosomes
Define: Synapsis
A process during which homologous chromosomes come together as pairs. It is during this process that four-chromatid complexes called tetrads are made.
Define: Homologous chromosomes
Chromosomes that have the same size, shape, and genes, but may contain different versions of these genes
Define: Crossing over
The process in meiosis (specifically prophase I) during which two non-sister chromatids exchange elements of DNA, beginning when the two genetically different chromatids come into contact at the chiasma
Define: Mutation
An irreversible change in the nucleotide sequence of an organism’s genome
Define: Point mutation
A type of mutation that causes only a single nucleotide base to change, in addition to insertion or deletion of DNA or RNA
Define: Chromosome mutation
A change that affects protein production and can lead to alterations to a chromosome’s physical structure that are more or less harmful to its function
State the sequence of mitosis (4 phases)
Prophase
Metaphase
Anaphase
Telophase
State the sequence of mitosis (4 phases)
Prophase
Metaphase
Anaphase
Telophase
State the sequence of meiosis I (5 phases)
Prophase I Crossing over Metaphase I Anaphase I Telophase I
State the sequence of meiosis II (5 phases)
Prophase II Metaphase II Anaphase II Telophase II Cytokinesis
Describe the function of cell division in prokaryotes
In prokaryotes, the primary function of cell division is to make asexual reproduction possible.
Describe the function of cell division in eukaryotes
In eukaryotes, cell division is the primordial means for growth and reparation of cells. It also allows an organism to contribute unique DNA to its offspring.
Describe the function of cell division in eukaryotes
In eukaryotes, cell division is the primordial means for growth and reparation of cells. It also allows an organism to contribute unique DNA to its offspring.
State the result of mitosis
Mitosis results in 2 new daughter cells that are identical to their parents and each other.
State the result of meiosis
As opposed to mitosis, meiosis results in four new haploid cells. The process is specific to sexual reproduction, and also results in the production of gametes.
How does meiosis increase genetic variability?
Offspring that result from sexual reproduction are highly varied, as they are genetically different from their parents and from one another. Crossing over during meiosis also adds variability, because it involves combining the genes from two genetically diverse non-sister chromatids.
How does meiosis increase genetic variability?
Offspring that result from sexual reproduction are highly varied, as they are genetically different from their parents and from one another. Crossing over during meiosis also adds variability, because it involves combining the genes from two genetically diverse non-sister chromatids.
Describe sister chromatids
Sister chromatids are identical to one another. They are conjoined at a common centromere. They equal one-half of a duplicated chromosome.
List the five event common to prophase in both mitosis and meiosis
The nucleus disappears The nucleolus dissolves The chromosomes condense Spindle fibers form to traverse the cell Centrioles begin to move to opposite poles of the cell
Outline the steps of meiosis (I and II)
Meiosis I
Prophase I: synapsis, crossing over, tetrads become visible
Metaphase: tetrads (now visible) align at the center of the cell
Anaphase I: tetrads begin to separate and chromosome pairs shift toward opposing ends of the cell, while the sister chromatids remain intact
Telophase: each pole now contains a haploid set of chromosomes
Outline the steps of meiosis (I and II)
Meiosis I
Prophase I: synapsis, crossing over, tetrads become visible
Metaphase I: tetrads (now visible) align at the center of the cell
Anaphase I: tetrads begin to separate and chromosome pairs shift toward opposing ends of the cell, while the sister chromatids remain intact
Telophase: each pole now contains a haploid set of chromosomes
Meiosis II
Prophase II: (identical to prophase I: preparatory)
Metaphase II: independent sister chromatids align at center
Anaphase II: chromatids separate
Telophase II: each side of the 2 resulting cells contains the haploid number of chromosomes
Outline the steps of meiosis (I and II)
Meiosis I
Prophase I: synapsis, crossing over, tetrads become visible
Metaphase I: tetrads (now visible) align at the center of the cell
Anaphase I: tetrads begin to separate and chromosome pairs shift toward opposing ends of the cell, while the sister chromatids remain intact
Telophase: each pole now contains a haploid set of chromosomes
Meiosis II
Prophase II: (identical to prophase I: preparatory)
Metaphase II: independent sister chromatids align at center
Anaphase II: chromatids separate
Telophase II: each side of the 2 resulting cells contains the haploid number of chromosomes
Cytokinesis: results in 4 haploid daughters that are each genetically unique
Explain crossing over
Crossing over occurs when 2 non-sister chromatids exchange genetic material during prophase I. It increases genetic variability in sexually reproducing organisms and is therefore very important to sexual reproduction.
Compare cytokinesis in plants and animals. There is ONE primary difference between the two processes.
Cytokinesis in both plants and animals begins toward the conclusion of telophase. However, in plants, the rigid cell wall prevents the cell from “pinching in” like in animal cells.
Compare gametes and somatic cells
Gametes is the collective term used for sex cells in animals, or the sperm and the egg.
Somatic cells, on the other hand, include every other body cell.
Compare haploid cells and diploid cells
A cell is said to be haploid when it contains only a single set of chromosomes.
Conversely, a cell is diploid if it contains two complete sets of chromosomes.
What is the formula for calculating the number of possible combination of chromosomes in a sexually reproducing organism? (Hint: the equation consists of a number and a coefficient.)
The formula for calculating the number of possible combination of chromosomes in a sexually reproducing organism is 2n, where coefficient n is the haploid number,
What is the formula for calculating the number of possible combination of chromosomes in a sexually reproducing organism? (Hint: the equation consists of a number and a coefficient.)
The formula for calculating the number of possible combination of chromosomes in a sexually reproducing organism is 2n, where coefficient n is the haploid number.
Name the three possible outcomes of mutation
Deletion
Insertion
Substitution
Compare point mutation and chromosomal mutation
A point mutation affects only a single portion of DNA or RNA or a base, while a chromosomal mutation goes on to alter long segments of a chromosome’s structure.
Describe spontaneous mutation
Spontaneous mutations arise from complications in replication. During spontaneous mutations, different genes mutate at various rates.
Describe spontaneous mutation
Spontaneous mutations arise from complications in replication. During spontaneous mutations, different genes mutate at various rates.
Describe induced mutations
Induced mutations are often caused (or induced) by environmental factors that stimulate change in DNA.
Compare substitution and insertion, two different outcomes of mutation
Substitution is the replacement of one nucleotide by another one (i.e. a purine and a pyrimidine)
On the contrary, insertion is the addition of one or more bases to a region of the DNA.
Describe inversion (chromosomal mutation)
Inversion occurs when genes appear reversed because some pieces of a chromosome have been flipped.
Describe translocation (chromosomal mutation)
Translocation occurs when pieces from one chromosome are moved to another. (Hence trans - location)
Describe duplication (chromosomal mutation)
Duplication occurs when chromosomes repeat themselves, creating duplicatees
Describe duplication (chromosomal mutation)
Duplication occurs when chromosomes repeat themselves, creating duplicate segments.
Describe insertion (chromosomal mutation)
When pieces are added to a chromosome
Describe deletion (chromosomal mutation)
When pieces are lost
Describe nondisjunction
Nondisjunction is an overflow of chromosomes in a gamete caused by homologous chromosomes’ failure to separate.
What is the name of the site where two sister chromatids come together during crossing over?
The chiasma (pl. chiasmata)
State the name of the process that restores the diploid number after meiosis
Fertilization
