BIO206: Mitosis/Meiosis, Probability, Reebops,


what are the two forms of DNA

chromatin and chromosome

4 characteristics of chromatin

uncondensed DNA
replicates easily
difficult to move
difficult to see under a microscope

4 characteristics of a chromosome

condensed DNA
difficult to replicate
moves easily
easy to see under microscope

what is DNA

found in the nucleus or nuceloid of ALL cells
stores genetic information

what is cell division

dividing process cells go through to make more cells and pass on their DNA

what are the two major cell division processes

mitosis: division of somatic cells
meiosis: division of germ cells

why is meiosis so important

forms the basis for sexual reproduction
gametes produced from meiosis can be sperm, eggs, pollen, or ovules
creates genetic diversity

where does mitosis happen

somatic cells

where does meiosis happen

germ cells

what happens during mitosis

the original cell copies DNA once and divides once

what happens during meiosis

the original cell copies DNA once and divides twice

results of mitosis

2 new somatic cells each with a full set of chromosomes identical to the original

results of meiosis

4 new cells called gametes each with 1/2 the amount of chromosomes present in the original germ cell

what is diploid

2 copies of each chromosome
-human somatic cells are diploid

what is haploid

1 copy of each chromosome
-human gametes are haploid

how do you identify and count chromosomes

use the centromeres

meiosis is essential for _________

sexual reproduction

what is meiosis the basis for

genetic variation- needed for evolution to occur (gradual change in species over time)

what is genetic diversity

differences between organisms of the same species

what is crossing over

chromatids cross and exchange genetic information in equal amounts
takes place during late prophase 1

what is independent assortment

pairs of homologous chromosomes line up and separate independently of one another
-occurs at the metaphase plate
-begins during prophase 1
-continues through metaphase 1
-ends in anaphase 1

what is segregation

the separation of pairs of homologous chromosomes
-takes place during anaphase 1

name the order 1-12 of mitosis

1- pre s phase
2- early prophase 1
3- middle anaphase 1
4- late prophase 1
5- metaphase 1
6- anaphase 1
7- telophase 1
8- interkinesis
9- prophase 2
10- metaphase 2
11- anaphase 2
12- telophase 2

what is a gene

a segment of a chromosome which determines a specific inherited characteristic/trait (such as the number of humps in reebops)

what is an allele

alternate forms of genetic information for a single trait (such as M or m, for the number of humps in reebops)
-there are alternate forms, so an allele only exists as a complement to another. an allele without an alternate form somewhere in nature does no

what is locus

the actual physical area (location) on the DNA where the gene is found

what is a genotype

a collection of alleles which form the genetic make-up of an organism (MM, Mm, or mm for example)

what is a phenotype

the physical appearance of the organism (1 antenna or 2 antenna for example). the physical expression of the genotype
-it is important to realize that there is often more than one genotype that codes for a certain phenotype

what is a gamete

the haploid cell that is the end product of meiosis

what is fertilization

the actual union of two gametes, which then fuse into one cell containing the original number of chromosomes

what is a zygote

the diploid cell resulting from fertilization

what is probability

-random alignment of chromosomes during metaphase 1 and eventual distribution in the gametes
-used to calculate likelihood of certain events

what do we use chi square for

test to determine how closely the data matches our prediction

what is the point of chi square

helps us analyze the observed data
-helps us determine if the difference between what we expected to happen and what we observed was simply due to random error or some other factor is influencing the results

what is random error

natural error that happens by chance

list general steps of chi square

-use probability to determine what we expect to happen
-compare what we expected to happen to the observed data
-determine chi square value
-determine the p-value (the probability that the difference between what we expected to happen and what we observed

when there is a relatively small difference between what is expected (e) and what is observed (o) ....

we get a small chi-square and a large p-value
-this means that there is a high probability that the difference was simply due to random error

when there is a large difference between what is expected (e) and what is observed (o)....

we get a large chi-square and a small p-value
-this means that there is a low probability that the difference was due to random error
-there must have been some other factor(s) that caused the difference

why do we use models in science

-easy to access
-easy to manipulate

what are specific advantages of using reebops to study genetics over actual animals such as mice

-do not need to wait for each generation to reproduce
-scaled down genetics
-easily identifiable traits
-easier to care for
-no accidental or unplanned mating

what are some disadvantages of using reebops

-over simplified in some ways
can't replicate chromosomes, can't show crossing over

looks at one trait and the possible combinations of alleles to produce different genotypes and phenotypes for that trait

monohybrid cross

looks at two traits and the possible combinations of alleles to produce different genotypes and phenotypes for these two traits

dihybrid cross

represented by big letters, shows its effect when present in a heterozygote, it masks the effect of a recessive allele

dominant alleles

represented by small letters, only shows its effect in the phenotype when present in a homozygote, the effect is hidden when paired with dominant allele

recessive alleles

two copies of the same allele for each trait

homozygous genotype

one dominant allele and one recessive allele for each trait

heterozygous genotype

tool to look at combinations of alleles and the resulting phenotypes and genotypes
-this tool can also be used to determine what expected genotype ratios and expected phenotype rations we would likely see from a cross between individuals with given phenot

punnett square







based on outcome of punnett square for the cross between two f1 organisms

expected f2 ratio

what is the "and" rule

two simultaneous outcomes with both occurring at the same time

what is the "or" rule

either one outcome or the other outcome will occur