Chapter 9 (so. far)
Ch.9 HW #1 #1A Nucleoli are present during #1B Cytokinesis often, but not always accompanies, #1C Chromosomes become visible during #1D Centromeres divide and sister chromatids become full-fledged chromosomes during #1E Spindle fibers attach to kinetochores during
#1A: Interphase #1B: Telophase #1C: Prophase #1D: Anaphase #1E: Prometaphase
Ch.9 HW #2 #2A #2B During _______ both the contents of the nucleus and the cytoplasm are divided #2C During ______ the cell grows and replicated both its organelles and its chromosomes
#2A: E #2B: The mitotic phase - the mitotic phase encompasses both mitosis and cytokinesis #2C: Interphase
Obj. 10.2) Recognize at which point cells become haploid, when homologous chromosomes (containing alleles) segregate, how many replications and divisions take place? What is the total number of resulting cells?
- Cells become haploid when they contain only 1 set of chromosomes (gamete cells) -They become haploid during meiosis I telophase I - the haploid number is 23, (n) -homologous chromosomes (containing alleles) segregate during meiosis I anaphase I - How many replications and divisions take place DNA replication occurs once during interphase before meiosis I and then 2 divisions occur - The total number of resulting cells is 4 daughter cells.
Obj. 10.3) Know independent assortment, crossing over, random fertilization
1. Independent assortment is the random orientation of pairs of homologous chromosomes at metaphase I
HW CH.10 QUESTION 3 If the DNA content of a diploid cell in the G1 phase of the cell cycle is represented by x, then the DNA content of the same cell at metaphase of meiosis I would be __
2x
HW CH.10 PRE-TEST QUESTION 2 What number and types of chromosomes are found in a human somatic cell?
44 autosomes and 2 sex chromosomes - Human somatic cells contain 22 pairs of autosomes and either two X chromosomes (in females) or an X and a Y chromosome (in males)
How many chromosomes do somatic cells in humans have?
46 chromosomes -two sets of chromosomes (23 pairs) - this is known as diploid number 2n/46 or a diploid cell -duplicated during interphase to 92 chromosomes
HW Ch.9 Pre-Test Question 1 A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain?
92 1 chromosome = 2 chromatids
HW Ch.9 Question 1 Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely a ___
A plant cell in the process of cytokinesis
HW CH.10 ACTIVITY ASEXUAL AND SEXUAL LIFE CYCLES PART A: Human gametes are produced by? PART B: Normal human gametes carry __ chromosomes PART C: Which of these cells are haploid? PART D: A diploid organisms whose somatic cells each contain 32 chromosomes produces gametes containing __ chromosomes?
A: Meiosis - meiosis produces haploid gametes from a diploid parent cell B: 23 - this is the number of chromosomes in a single set of human chromosomes C: C & D - once meiosis 1 is completed, cells are haploid D: 16
HW CH.10 MEIOSIS ANIMATION PART A: Meiosis I produces __ cells, each of which is __. PART B: Meiosis II typically produces __ cells, each of which is __ PART C: During __ sister chromatids separate PART D: At the end of __ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids PART E: Synapsis occurs during __ PART F: Homologous chromosomes migrate to opposite poles during __ PART G: During __ chromosomes align single file along the equator of a haploid cell PART H: At the end of __ and cytokinesis, there are four haploid cells PART I: During __ a spindle forms in a haploid cell.
A: two; haploid B: four; haploid C: Anaphase II D: Telophase I E: Prophase I F: Anaphase I G: Metaphase II H: Telophase II I: Prophase II
Obj. 9.3) Compare cytokinesis in animal and plant cells
Animal Cells - cytokinesis occurs by a process called cleavage - the first sign of cleavage is appearance of the cleavage furrow ( a shallow groove in the cell surface near the old metaphase plate) 1. On the cytoplasmic side of the furrow is a contractile ring of actin microfilaments associated with molecules of the protein myosin. 2. The actin filaments interact with the myosin molecules, causing the ring to contract. 3. The cleavage furrow deepens until the parent cell is pinched in 2, producing 2 completely separate cells, each with their own share of cytosol, organelles, and other subcellular structures. Plant Cells - THERE IS NO CLEAVAGE FURROW 1. During telophase, vesicles derived from the golgi apparatus move along microtubules to the middle of the cell, where they coalesce (fuse) to produce a cell plate. 2. Cell wall materials carried in the vesicles collect inside the cell plate as it grows. 3. The cell plate grows until its membrane fuses with the plasma membrane of the plant cell 4. Two daughter cells result, each with their own plasma membrane 5. A new cell wall arising from the contents of the cell plate forms between the daughter cells
Somatic cells
Any cells in the body other than reproductive cells
HW Ch.9 Misconception Question 59 How do cancer cells differ from normal cells?
Cancer cells may be immortal
HW CH.9 Question 5 The drug cytochalasin B blocks the function of actin. Which of the following aspects of the animal cell would be most disrupted by cytochalasin B?
Cleavage furrow formation and cytokinesis -actin microfilaments are used during cytokinesis for the contraction of dividing cells in cleavage furrow formation
Chromosomes
Composed of 1 DNA molecule and associated protein molecules. - In a eukaryotic cell there are multiple linear chromosomes located in the nucleus - In a prokaryotic cell there is a singular circular chromosome located in the nucleoid, a region that is not enclosed by a membrane In a eukaryotic cell there are 2 sets of 23 pairs of chromosomes (one set inherited from each parent ) - Reproductive cells only have 1 set (23 pairs)
HW Ch. 9 Misconception Question 57 Which statement provides the best description of the interphase portion of the cell cycle?
During interphase a cell is metabolically active - chromosome duplication occurs during the s phase of interphase - interphase makes up about 90% of the cell cycle and is critical to the cell cycle, therefore it is not a rest phase
HW Ch. 9 Misconception Question 56 If a eukaryotic cell is in the G1 phase of the cell cycle, which statement about the cell's chromosomes must be correct?
Each chromosome is made of a complex of DNA and associated proteins -Eukaryotic nucleus contains chromatin, a complex of DNA and associated protein molecules. The proteins maintain the structure of the chromosomes and help control gene activity
HW Ch.9 Pre-Test Question 7 Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle?
G1
HW Ch.9 Question 4 A particular cell has half as much DNA as some other cells in a mitotically active tissue. The cell in question is most likely in __
G1 -This cell has yet to start it's S phase, where DNA will be duplicated
HW Ch.9 Pre-Test Question 4 Which of the following correctly matches a phase of the cell cycle with its description?
G1: Follows cell division
HW CH.10 PRE-TEST QUESTION 5 How are sister chromatids and homologous chromosomes different from each other?
Homologous chromosomes contain the same gene loci but may have different alleles of a particular gene. Sister chromatids are identical copies of each other produced during DNA replication. - one homologous chromosome comes from the father and one from the mother. Sister chromatids are identical copies of each other.
Obj. 11.2) Homozygous vs Heterozygous
Homozygous is having two identical alleles for a given gene. An organism that has a pair of identical alleles for a gene encoding a character is called a homozygote. Ex: the purple flower (PP) and the white flower (pp) are homozygous Heterozygous is having two different alleles for a given gene. An organism that has two different alleles for a gene is called a heterozygote.
HW CH.10 QUESTION 2 Homologous chromosomes moved toward opposite poles of a dividing cell during __
Meiosis I -during anaphase I
Obj. 10.1) Describe the role of meiosis in the sexual life cycle. - Why is it important? - What would happen to the chromosome number during fertilization if there were no meiosis?
Meiosis is a modified type of cell division in sexually reproducing organisms consisting of two rounds of cell division but only one round of DNA replication. It results in cells with half the number of chromosome sets as the original cell. - Meiosis is important for counterbalancing the doubling that occurs during fertilization. - If there were no meiosis, during fertilization the chromosome number would double from 46 to 92, and then continue to double with each generation.
Obj. 11.2) Genotype vs phenotype
Phenotype is an organism's appearance or physical and physiological traits. Determined by its genetic makeup. Genotype is the genetic makeup or set of alleles, of an organism.
HW CH.10. PRE-TEST QUESTION 1 Asexual reproduction generally
Produces offspring genetically identical to the parent
HW Ch.9 Question 3 Which of the following does not occur during mitosis?
Replication of the DNA -This occurs during the S phase of interphase
Obj. 9.1) Identify and recognize the stages of the cell cycle, and describe the principle events of each stage
Stages of the cell cycle - Interphase - Includes: G1, S , G2 - Mitotic Phase - Includes: Prophase, prometaphase, metaphase, anaphase, telophase
Obj. 9.4) Understand how the eukaryotic cell cycle is regulated including the major checkpoints and contributing factors such as cyclins & cyclin-dependent kinases
The G2 checkpoint ensures all of the chromosomes have been replicated and that the duplicated DNA is not damaged before cell enters mitosis. The M checkpoint determines whether all the sister chromatids are correctly attached to the spindle microtubules before the cell enters the irreversible anaphase stage.
HW CH.10 PRE-TEST QUESTION 3 For what purpose might a karyotype be prepared?
The first three answers are correct - karyotypes can show if all the of the chromosomes are present and whether an individual is male (XY) or female (XX). In addition, by staining the chromosomes and examining the resulting band patterns, it is possible to detect defects such as deletions, translocations, and inversions
Genome
The genetic material of an organism or virus. The complete complement of an organism's or virus's genes along with its noncoding nucleic acid sequences. -a cell's endowment of DNA, its genetic info
HW Ch.9 Pre-Test Question 3 Which of the following is true of kinetochores?
They are the sites at which microtubules attach to chromosomes
HW Ch.9 Misconception Question 58 What is true of all cancers?
They have escaped normal cell cycle controls
HW Ch.9 Pre-Test Question 2 Why is it difficult to observe individual chromosomes with a light microscope during interphase?
They have uncoiled to form long, thin strands
HW Ch.9 Pre-Test Question 9 Why do some species employ both mitosis and meiosis, whereas other species only use mitosis?
They need both if they are reproducing sexually -Organisms the reproduce asexually use only mitosis
HW Ch.9 Pre-Test Question 8 Which of the following is true of benign tumors but not malignant tumors?
They remain confined to their original site -Benign tumors can be surgically removed because their boundaries are well defined, whereas some malignant tumors go on to metastasize
HW CH.10 QUESTION 1 A human cell containing 22 autosomes and a Y chromosome is__
a sperm
HW Ch.9 Question 2 In the cells of some organisms, mitosis occurs, WITHOUT cytokinesis. This will result in __
cells with more than one nucleus Explanation: without cytokinesis the cytoplasm and nuclei will not divide between two cells.
HW Ch.9 Pre-Test Question 6 Cytochalasin B is a chemical that disrupts microfilament formation. How would this interfere with cell division?
cleavage -in animal cells, the cleavage furrow forms when a ring of microfilaments contracts, causing the parent cell to be pinched into two.
HW Ch.9 Pre-Test Question 5 In some organisms, such as certain fungi and algae, cells undergo the cell cycle repeatedly without subsequently undergoing cytokinesis. What would result from this?
large cells containing many nuclei
Obj. 11.2) monohybrid cross vs dihybrid cross vs Test Cross
monohybrid cross is a cross between two organisms that are heterozygous for the character being followed (or the self-pollination of a heterozygous plant) - monohybrid is an organism that is heterozygous with respect to a single gene of interest. All of the offspring from a cross between parents homozygous for different alleles are monohybrids. Ex: Parents of genotypes AA and aa produce a monohybrid of genotype Aa. dihybrid cross is a cross between two organisms that are each heterozygous for both of the characters being followed (or the self-pollination of a plant that is heterozygous for both characters) - dihybrid id an organism that is heterozygous with respect to two genes of interest. All the offspring from a cross between parents doubly homozygous for different allele. Ex: Parents of genotype AABB and aabb produce a dihybrid of genotype AaBb. Test cross
Gametes
reproductive cells
HW CH.10 PRE-TEST QUESTION 7 Which of the following occurs during meiosis but not during mitosis?
synapsis occurs - The pairing of homologous chromosomes that only occurs during prophase I of meiosis is called synapsis.
HW CH.10 PRE-TEST QUESTION 8 What is crossing-over?
the exchange of homologous portions of nonsister chromatids -the result of the exchange of homologous portions of nonsisiter chromatids is the new combinations of genetic materials (genetic recombination)
Obj. 11.2) True breeding vs hybrid (Mendel's terminology)
true breeding refers to organisms that produce the same variety of offsprings over many generations of self-pollination. Ex: a plant with purple flowers is true breeding if the seeds produced by self pollination in successive generations all give rise to plants that also have purple flowers hybrid is the crossing of two true breeding organisms
HW CH. 10 PRE-TEST QUESTION 6 Mitosis results in the formation of how many cells; meiosis results in the formation of how many cells?
two diploid cells...four haploid cells - In mitosis, a cell that has doubled its genetic material divides to produce two diploid daughter cells. In meiosis, a cell that has doubled its genetic material undergoes two rounds of division, producing four haploid cells.
HW CH.10 QUESTION 4 If the DNA content of a diploid cell in the G1 phase of the cell cycle is represented by x, then the DNA content of the same cell at metaphase of meiosis I would be 2x. If we continued to follow the cell lineage, the DNA content of a cell at metaphase of meiosis II would be __________.
x
