• Tens of thousands
– Each chromosome has hundreds or thousands of genes; the entire human genome has on the order of 20,000 to 25,000 genes.
– Each chromosome has hundreds or thousands of genes; the entire human genome has on the order of 20,000 to 25,000 genes.
How many genes are present in the human genome?
• The precise location of a gene on a chromosome
-The location of a gene within the genome, including the identity of the particular chromosome that it maps to and its specific position on that chromosome
-The location of a gene within the genome, including the identity of the particular chromosome that it maps to and its specific position on that chromosome
What is a locus?
• They can both occur in multicellular organisms
Sexual and asexual reproduction are alike in that __________.
• Asexual reproduction and mitosis
-In asexual reproduction, an organism produces genetically identical progeny, or clones, by mitosis.
-In asexual reproduction, an organism produces genetically identical progeny, or clones, by mitosis.
A clone is the product of __________.
• A diploid zygote
-Fertilization always involves the fusion of gametes and produces a diploid zygote.
-Fertilization always involves the fusion of gametes and produces a diploid zygote.
Fertilization produces __________.
• Mitosis, meiosis, and fertilization
The sexual cycle of the diploid, multicellular algal genus Fucus involves __________.
• Fungi
A life cycle in which the only multicellular form is haploid is most typical of __________.
• Meiosis…fertilization
-Meiosis reduces the number of chromosomes by half, and fertilization restores the number to the diploid state.
-Meiosis reduces the number of chromosomes by half, and fertilization restores the number to the diploid state.
In sexually reproducing species, the chromosome number remains stable over time because __________ and __________ always alternate.
• 44
The egg (ovum) of a rabbit contains 22 chromosomes. How many chromosomes are in the somatic (body) cells of a rabbit?
• 5
In a diploid cell containing 10 chromosomes, meiosis results in the formation of daughter cells containing __________ chromosomes.
• 22
How many pairs of autosomes do humans have?
• Are identical copies of each other formed through DNA synthesis
Sister chromatids __________.
• They have genes for the same traits at the same loci.
Which of the following statements about homologous chromosomes is correct?
• Its cells have a single set of chromosomes
When we say that an organism is haploid, we mean that __________.
• Multiplication of body cells
Which of the following is a function of mitosis in humans?
• Two … diploid
Somatic cells in humans contain __________ set(s) of chromosomes and are therefore termed __________.
• At fertilization, when gametes fuse
Nearly all life cycles have both haploid and diploid phases. Usually, the transition from haploid to diploid takes place __________.
• Gametes never resemble spores morphologically
Spores and gametes are different in that __________.
• Liver cells
Humans have 46 chromosomes. This number of chromosomes will be found in __________.
• Meiosis
What results in cells that contain half the parental chromosome number?
• Two haploid cells
At the end of telophase I of meiosis and the first cytokinesis, there are __________.
• Four haploid cells
What is the typical result when a diploid cell has completed meiosis?
• Prophase I
Synapsis occurs during __________.
• Sister chromatids separate and migrate toward opposite poles.
What occurs during anaphase II?
• Homologs separate and migrate toward opposite poles.
What occurs during anaphase I?
• Division of the cytoplasm to create two cells
Cytokinesis is the __________.
• To make cells with a haploid (half that of the parents) number of chromosomes
What is the function of meiosis?
• Prophase I
Crossing over occurs during __________.
• Chiasmata
Regions of chromosomes where nonsister chromatids cross over are called __________.
• Physically connects homologous chromosomes during prophase I
-The synaptonemal complex helps to line up homologous chromosomes gene by gene.
-The synaptonemal complex helps to line up homologous chromosomes gene by gene.
The synaptonemal complex __________.
• 4
An organism has a haploid chromosome number n = 4. How many tetrads will form during meiosis?
• Synapsis of homologous pairs occurs.
Which event occurs only during prophase I of the first meiotic division?
• Homologous chromosomes separate.
Which of the following occurs in meiosis, but NOT mitosis?
• Decreasing the chromosome number to haploid
• Introducing genetic variation among the daughter cells
• Ensuring that each daughter cell gets a single, complete set of chromosomes
• Undergoing two rounds of cytokinesis
• Introducing genetic variation among the daughter cells
• Ensuring that each daughter cell gets a single, complete set of chromosomes
• Undergoing two rounds of cytokinesis
What makes meiosis lengthier and more complex than mitosis?
• 16
Ignoring crossover events, how many kinds of gametes can be produced by an organism with a diploid number of 8?
• Random fertilization, independent assortment, crossing over
Which of the following contributes to genetic variation in sexually reproducing species?
• 2^23
In humans, the haploid number of chromosomes is 23. Independent assortment has the possibility of producing __________ different types of gametes.
• They align and assort independently to form any of 16 different combinations.
The diploid number of chromosomes in a certain animal is 8 (2n = 8). How do the four pairs of homologous chromosomes align and separate during meiosis?
• 1/8
In a diploid set of chromosomes, one member of each pair of homologous chromosomes is derived from the father (paternal), and the other comes from the mother (maternal). If 2n = 6, what is the probability that a particular gamete will contain only paternal chromosomes?
• It provides a method to increase genetic variation
The major contribution of sex to evolution is that __________.
• The random alignment of homologous pairs of chromosomes at metaphase I
Which of the following answers is NEITHER involved with crossing over NOR an outcome of crossing over?
• Although energetically more costly than asexual reproduction, sexual reproduction leads to different combinations of alleles that could provide adaptability in a changing environment.
Which of the following statements reflects an advantage that sexual reproduction likely provides over asexual reproduction?
• Sexual reproduction … reproduce asexually but can increase genetic variation present in a population by means of the uptake of DNA from other rotifers
Although __________ is nearly universal among animals, bdelloid rotifers __________.
Mitosis and meiosis
Diploid cells can divide by ___________
Mitosis NOT meiosis
Haploid cells can divide by _______
• Multicellular haploid stage (gametophyte), multicellular diploid stage (sporophyte), zygote, and spores
List what all is apart of the life cycle called alternation of generations
