Test 1 Flashcards
What is the common name of Drosophila Melanogaster?
Fruit Fly
What is the common name of Coenorhabditis elegans?
Roundworm
What is the common name of Arabidopsis Thaliana?
Thale Crest
What is the common name of Mus Musculus?
House Mouse
What is the common name of Zea mays?
Corn
What is the common name of Neurospora Crassa
Bread Mold
What is the common name of Macaca Mulatta?
Rhesus Monkey
What is the common name of Xenopus Laevis?
African Clawed Frog
What is the common name of Rattus Norvegicus?
RAT
What is the common name for Danio Rerio?
Zebra Fish
What are characteristics of a good model organism?
- Small Size
- Controlled breeding- easy to breed to specific individuals
- Raising-Easily raised in a laboratory setting without losing a lot of money
- Biological Knowledge- the more we already know the better
- Genome size- one we have already sequenced or know a lot about
- Interesting, useful and unusual
- Life cycle- Not a long generation time, something we can easily observe
- Ethics- the closer the “model” gets to humans or having human like characteristics, the more problems society will have when it is being used for scientific research
- Liablilities- the fewer the better
Gene (locus)
genetic factor that helps determine a trait, at the molecular level it is the sequence of DNA that is transcribed into an RNA molecule
Allele
One of two or more alternate forms of a gene
Chromatin
material found in the eukaryotic nucleus consisting of DNA and protein; another name fore the DNA after it is packaged to fit into the cell
Chromosome
Structure of DNA and associated proteins that carries one of the DNA molecules
Sister chromatids
The two chromosomes that are attached to the same centromere after replication
Homologous Chromosomes
chromosomes that have the same length, centromere positions and genetic loci, but can have different alleles
autosome
chromosomes that are the same in both sexes
Phenotype
what individual looks like
Locus
position of a gene on a chromosome (loci=plural form)
Genotype
allele composition usually represented by using letter abbreviations for alleles
Sex Chromosomes
differ between sexes
Stages of Mitosis and number of chromatids are attached to the centromere in each stage
Prophase (2)
Metaphase (2)
Anaphase (1)
Telophase (1)
resulting in two daughter cells
Cytokinesis
The division of the cytoplasm
What is the purpose of checkpoints in Mitosis
Key transition points in the cell cycle
What do functional Eukaryotic chromosomes contain?
Telomere
Centromere
At least one origin of replication
Substages of prophase I in Meiosis
Leptotene- chromosomes begin to coil up and chromosomes are visible
Zygotene- Homologous chromosomes synapse
Pachytene- Crossing over occurs between non sister chromatids of homologous chromosomes
Diplotene- homologous centromeres begin to repel from each other
Diakinesis- Terminalization of the chiasmata occurs as homologous centromeres continue to repel
Stages of Meiosis and number of chromatids are attached to the centromere in each stage
Prophase I (2) Metaphase I (2) Anaphase I (2) Telophase I (2) Prophase II (2) Metaphase II (2) Anaphase II (1) Telophase II (1)
4 meiotic products
What are the roles of Cohesin and Shugoshin in mitosis and meiosis?
Cohesin- holds sister chromatids together in mitosis and meiosis. It also acts as chiasmata in meiosis to hold homologs together (different forms of this protein in mitosis and meiosis)
Shugoshin (guardian Spirit)- protects cohesio at the centromere in anaphase I of meiosis, but is degraded by anaphase II. This allows homologs to separate in anaphase I but keep the sister chromatids together.
Comparing Mitosis and Meiosis
Mitosis:
- one division results in 2 daughter cells
- Chromosome number per nucleus maintained in mitotic products
- 1 pre-mitotic S phase per cell division
- Normally, no pairing of homologous chromosomes
- Normally, no cross overs
- Centromeres divide in anaphase
- Conservative process: daughter cell genotypes are exactly like parent cell
- Cell undergoing mitosis can be diploid or haploid
Meiosis
- Two divisions result in 4 products of meiosis
- chromosomes number halved in meiotic products
- 1 pre-meiotic S phase per meiotic process (2 divisions)
- Homologous chromsomes synapse
- Usually, at least one cross over per homologous pair
- Centromeres do not divide in anaphase I but do divide in anaphase II
- Promotes variation among products of meiosis
- Works best with diploid cells
How does meiosis provide variation from generation to generation?
- Crossing over allows each chromosome to contain some maternal and some paternally derived alleles
- Suffling of maternal and paternal chromosomes (independent Assortment)
What studies are important in cancer research?
Cell cycle and regulation studies
Nondisjunction
mistakes in separation of chromosomes in meiosis
Karyotype
an organized array of an individuals chromosomes
When does nondisjunction occur and what happens?
can occur in either the first or second anaphase in meiosis
results in gametes with an abnormal number of chromosomes
Mendel’s law of Random Segregation
- The two alleles of a locus do not blend or fuse
- During gamete formation in a heterozygous individual, half of the gametes will receive one of the alleles and half of the gametes will receive the other allele
- This results in an individual of a genotype Aa producing two types of gametes in equal frequency
Mendel’s law of independent assortment
- During gamete formation in an individual who is heterozygous for two loci, the allele from the first locus that goes into a particular gamete will not influence which allele at the other locus goes into the gamete
- This results in an individual of genotype AaBb producing four types of gametes in equal frequency: AB, Ab, aB, and ab
Product rule and its uses
probability of two or more independent events occurring together is the product of their probabilities.
- clue “and” in a word problem
- P(A and B)= P(A)* P(B)
Addition rule
the probability of two or more mutually exclusive events is the sum of their probabilities
characteristics of a homologous chromosome
same length, centromere position, banding pattern, and genetic loci
What are the two ways that meiosis producing 4 meiotic products?
1) reductional division- number of chromosomes in the daughter cell is half the number in the original cell (one of each homologous pair in each daughter cell)
2) Equational division- number of chromosomes at the beginning and end of the division cycle is the same, but the daughter cell only have one chromatid
What is simple mendelian inheritance?
- one allele is completely dominant to the other (unless otherwise specified in the hypothesis
- Random segregation occurs at all loci involved in the test
- Independent assortment occurs between all loci involved in the test
- Random Fertilization occurred in producing the individuals in the generation that is being tested
Protenor mode of sex determination is?
XX/XO- sexes have a different number of chromosomes
Females have 2 (XX) males have 1 (XO)
ex: grasshoppers, orthoptera
Lygaeus mode of sex determination?
XX/XY- sexes have same number of chromosomes, but one pair doesn’t look homologous
EX: fruit flies, us, mealworm
Heterogametic Sex
XY, XO
Homogametic sex
XX
Hemizygous
one copy of the chromosome is present
crossing bbxbb you get all bb’s
Holandric
only found in the males
Sex determination in Drosophila Melanogaster (fruit flies)
Calvin Bridges: Genic Balance theory
-Sex is determined by the ration of the number of X chromosomes to the number of autosomal sets
Normal Femal= xx/2a ratio of 1.0 Normal Male=XY/2A ratio is .5 below.5= sterile male in between .5-1= interest 1.5-= infertile femtal
Nondisjunction of the X chromosome results in gametes XX and 0. After fertilization, the following aneuploid types are formed. XXX, XXY, and XO, Y0 flies die.
What type of chromosome system does chicken birds and some fish use for sex determination?
ZZ= male ZW= female