Exam 3 quizlet
Compare and contrast mitosis & meiosis. Draw them side by side with labels. Make sure to include # of chromosomes and # of sister chromatids at each step. How are they similar? How are they different?
Both are forms of cell division with similar phases. interphase occurs before the cell divides. during division the cell goes through prophase, metaphase, a, t and cytokinesis takes place. Differences: Meiosis includes two divisions. Meiosis produces 4 new cells each having half the chromosomes of parent cells. shuffles genetic info so each new cell receives unique mixture of alleles. DNA replicates once in S phase but the nucleus divides twice.
How does diploid/haploid relate to mitosis & meiosis?
Diploid and haploid cells are formed after mitotic cell division and it maintains the cells original ploidy level (one diploid 2n cell producing two diploid 2n cells; one haploid n cell producing two haploid n cell
What is polyploidy? How is it different than aneuploidy? How do we represent polyploidy?
Extra complete set of chromosomes. common in plants. aneuploidy is extra or missing set of chromosome.
Walk me through the human life cycle: when are cells haploid? When are cells diploid? When does mitosis occur? When does meiosis occur?
Fertilization, development, meiosis, gamete formation. Germ cells undergo meiosis which produce gametes (sperm and egg cells) gametes do not divide. Gametes are haploid and are the only haploid cells in the life cycle. 1st step: gametes fuse and fertilize then create a zygote. Zygote then undergo mitosis and is a diploid cell. all body cells are genetically identical to the zygote.
What is monosomy and how is it caused?
Having one single copy of a chromosome. It's caused by nondisjunction in meiosis
What is crossing over/recombination? When does it occur? How could you draw it? How does it relate to genetic diversity?
In prophase 1; swapping out different parts of chromosomes from parental to maternal. random fertilization multiplies diversity
Meiosis II
Is like mitosis, but with no DNA replication. 1 diploid cell divides to 4 haploid cells at the end
Explain the differences between identical twins and fraternal twins.
Monozygotic twins: identical twins. One egg and one sperm and early development causes an embryo to split into two Fraternal twins: two separate embryos, 2 eggs, and 2 sperms
Meiosis 1 phases in order
Prophase 1: spindle forms, chromosomes condense and attach to spindles. then homologous chromosomes pair up and chromosomal crossover can take place. Metaphase 1: chromosomes line up in two rows. aligns randomly/independent assortment genetic diversity occurs in first two stages Anaphase 1: spindle separates the homologous chromosomes (not the sister chromatids) Telophase 1: chromosomes move to opposite sides of the cell, nuclei forms Cytokenesis 1: the cell splits into two new cells, in this stage it is a haploid cell because they have sister chromosomes
What is independent assortment? When does it occur? How could you draw it? How does it relate to genetic diversity?
Random alignment of chromosomes during metaphase 1 (in Meiosis) . When meiosis occurs and random alignment of different chromosomes occur it allows for differences and cause genetic diversity in physical features and internal features.
How does the process of fertilization contribute to genetic diversity?
When any egg of the mother combines with any of the sperm cell then it causes more genetic diversity.
what are the consequences of nondisjunction?
When during meiosis chromosomes fail to separate normally into 4 haploid cells 2 cells lack a chromosome and 2 have an extra copy Most of the embryos are not viable -- early miscarriages Most of these errors occur during meiosis in females; error rate increases with advanced maternal age. It is lethal and causes defects
How would you recognize that an organism hasaneuploidy?
When in cell division the chromosomes do not separate properly.
What is nondisjunction?
When in meiosis I nondisjunction may occur and this is when chromosomes do not separate properly. it becomes a diploid cell. In Meiosis two it will become haploid cells.
How wouldyou recognize that nondisjunction has occurred?
When there is three sets of chromosomes present in one cell or just 1. and defects occur
Could you look at a karyotype and determine if that individual has a trisomic disorder or monosomic disorder
Yes, you can.
homologous chromosomes
are matched sets. have the same gene in the same location. but different alleles. one mother and one father chromosome.
What does diploid mean? How do we represent diploid? What types of cells are diploid?
contains two sets of homologous chromosomes. We get one from each parent in which we have 23 chromosomes. 22 are called homologous autosomes
Allele
different version of the same protein.
What is aneuploidy?
extra or missing chromosomes. Example: trisomy where there is 3 chromosomes in one gamete. Downsyndrome, Edward syndrome
XX, XY
female and male
Mitosis creates
has two identical daughter cells.
What does haploid mean? How do we represent haploid? What types of cells are haploid?
having one set of chromosome. egg and sperm/gametes/germ cells are haploid
sister chromatids
identical set of alleles. whereas homologous has different alleles but it can have same genes.
Homologous chromosomes
not identical, sequence is different, carries different alleles but carries the same set of genes
What is meiosis
required for sexual reproduction. is genetically unique. only germ cells can carry out meiosis
Asexual/mitosis: produces identical offsprings, homologous chromosomes do not pair up, crossing over does not occur, is not adaptive. sexual/meiosis: does not create identical offsprings, needs two parents, homologous chromosomes pair up, adaptive. Both: Mutations occur
sexual and asexual
Karyotype
shows every chromosome in a cell
All cells in our body is called ?
somatic cells through mitosis
What is trisomy and how is it caused?
trisomy is a genetic disorder when a person has three copies of chromosomes instead of one