Download SBU Bio-202 Exam 4: Meiosis and Cell Division - Questions with Complete Solutions and more Exams Biology in PDF only on Docsity!
SBU Bio-202 Exam 4 Professor Erster Spring 2024 Questions With Complete Solutions Meiosis Process in which a diploid nucleus is converted into four haploid nuclei Meiosis I The reduction division because it reduces the chromosome number from diploid to haploid as the homologous chromosomes separate from one another Meiosis II The second phase of meiosis consisting of chromatids separating, along with the two diploid cells splitting in two Prophase I The chromosomes condense, and the nuclear envelope breaks down, crossing-over occurs Chiasmata Site of crossing over Telophase I Cytoplasm divides, 2 daughter cells are formed Prophase II A new spindle forms around the chromosomes
Metaphase II The duplicated chromosomes move to the center of the cell. Each centromere attaches to two spindle fibers instead of one Anaphase II Sister chromatids separate Telophase II Nuclear membrane reforms, cytoplasm divides, 4 daughter cells formed Functions of Cell Division Reproduction, growth and development, tissue renewal Chromosome A threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes Mitosis Part of eukaryotic cell division during which the cell nucleus divides How is DNA stored Chromosomes Somatic cells have
DNA replication Interphase Period of the cell cycle between cell divisions (G1, S, G2) M Phase The phase of the cell cycle that includes mitosis and cytokinesis G2 of Interphase (Full) Assembly of spindle microtubules begins in the centrosome, centrosome duplicates Prophase Chromosomes become visible, nuclear envelop dissolves, spindle forms Prometaphase Spindle microtubules attach to the kinetochores of chromosomes and begin to move the chromosomes Metaphase The chromosomes are all lined up at the metaphase plate between the spindle's two poles Anaphase Phase of mitosis in which the chromosomes separate and move to opposite ends of the cell Telophase
After the chromosome separates, the cell seals off Cytokinesis Division of the cytoplasm to form two separate daughter cells Cytokinesis in plants Cell plate forms a cell wall between the two daughter cells Binary fission A form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size Types of cells that cannot divide Nerve cells, muscle cells, red blood cells Cells that can if induced, but don't normally divide Liver cells, lymphocytes How is the cell cycle regulated? Controlled by regulatory protein checkpoints both inside and outside the cell Checkpoints in cell cycle G1/S, G2, anaphase Benefit of cellular checkpoints Slows down progression through the cell cycle so a cell has time to repair any errors from the previous step
- Unlimited replicative potential
- Angiogenesis
- Invasion and metastasis Ras gene A gene that codes for Ras, a G protein that relays a growth signal from a growth factor receptor on the plasma membrane to a cascade of protein kinases, ultimately resulting in stimulation of the cell cycle p Causes cell cycle arrest in G1, providing time for DNA repair. If repair is successful, cells re-enter the cycle. If unsuccessful, apoptosis Genetic change An alteration in DNA sequence that can change the protein product specified by a gene Epigenetic change Alter the pattern of gene expression, and can be passed down Asexual reproduction Process by which a single parent reproduces by itself Sexual reproduction A reproductive process that involves two parents that combine their genetic material to produce a new organism
Homologous chromosomes Chromosomes that have the same sequence of genes and the same structure Sister chromatids Identical copies of a chromosome; full sets of these are created during the S phase of interphase. Mechanisms of Genetic Variation
- Independent assortment of chromosomes
- Crossing over
- Random fertilization Independent assortment The random distribution of the pairs of genes on different chromosomes to the gametes Crossing over When homologous portions of two non-sister chromatids trade places Crossing over creates ___ chromosomes Recombinant Spermatogenesis Formation of sperm Oogenesis
Mendel's law that states that the pairs of homologous chromosomes separate in meiosis so that only one chromosome from each pair is present in each gamete Mendel's Law of Segregation explains the 3:1 ratio between F2 offspring Allele Different forms of a gene Phenotype Physical characteristics of an organism Genotype Genetic makeup of an organism Law of Independent Assortment The law that states that genes separate independently of one another in meiosis when do you use sum rule When there are two or more ways of obtaining the same outcome When do you use product rule Examples of Nonmendelian Inheritance Incomplete Dominance Codominance/ Multiple allelism
Pleiotropy Epistasis Continuous variation (polygenic inheritance) Environmental effects Sex-influenced Sex-limited Lethal Inheritance of characters by a single gene may deviate from simple Mendelian patterns when When alleles are not completely dominant or recessive When a gene has more than two alleles When a gene produces multiple phenotypes Complete Dominance A relationship in which one allele is completely dominant over another (red + white = red or white) Incomplete Dominance Situation in which one allele is not completely dominant over another allele, phenotypically a mix (red + white = pink) Codominance A condition in which neither of two alleles of a gene is dominant or recessive (red + white = red and white) Examples of codominance Blood type, AB
Mendelian genes have specific loci (positions) on chromosomes and chromosomes undergo segregation and independent assortment Thomas Hunt Morgan Used fruit flies to confirm the existence of sex-linked traits Morgan results The F1 generation all had red eyes The F2 generation showed the 3:1 red:white eye ratio, but only males had white eyes Proved the chromosome theory of inheritance Parental Type An offspring with a phenotype that matches one of the true- breeding parental (P generation) phenotypes; also refers to the phenotype itself Recombinant Types Offspring who have inherited new combinations of genes and have phenotypes that don't match either parental phenotypes Linked genes Genes located on the same chromosome that tend to be inherited together in genetic crosses. What did Morgan propose to explain linkage being incomplete sometimes?
Crossing over between non-sister chromatids of homologous chromosomes Each map unit represents A 1% chance of recombination Sex-determining chromosomes X and Y The __ chromosome has more than1000 genes and is essential X The __ chromosome is small and not essential Y XX Female XY Male PARs Homologous regions between X and Y that allow them to still behave as homologues during meiosis SRY Sex determining region of the Y chromosome Primary Feature
A human genetic disease caused by a dominant allele; characterized by uncontrollable body movements and degeneration of the nervous system; usually fatal 10 to 20 years after the onset of symptoms. Hemophilia X-linked recessive disorder Nondisjunction Error in meiosis in which homologous chromosomes fail to separate Genetic Imprinting Selective expression of either the maternal or paternal copy of a gene Maternal Inheritance Genes that are inherited only from the mother, such as mitochondrial genes (all organelles come only from the ovum). Extranuclear Genes Genes outside the nucleus, in the mitochondria and chloroplasts Multi-Factorial Disorders Combination of multiple genetic and environmental causes
