Mitosis
What is a somatic cell?
All cells in our body, except egg and sperm; produced by mitosis
What holds two homologous chromosomes together in a tetrad?
synaptonemal complex
What is the 1st Law: Principle of Segregation
the two versions (alleles) for a gene segregate during gamete formation (anaphase 1).
them thy are joined at random, one from each parent, during fertilization
What is the chiasmata
the site of crossover in meiosis 1
What is a common example of codominance?
ABO blood group in humans
What is a karyotype and why are chromosomes packaged the way they are in one?
A human karyotype is a picture of all chromosomes in a single cell. When chromosomes are condensed or tightly packed, they can b easily distinguished from each other. (when chromosomes are loosely packed or decondensed, it is not possible to distinguish them from each other)
What do germ-line cells do? And are they diploid or haploid
Divide by meiosis to produce egg or sperm (gametes, n) or can divide by mitosis to produce more germ line cells (2n)
What is the 2nd Law:Principle of Independent Assortment
Alleles of two different genes sort into gametes independently of each other during metaphase 1
At what phase of mitosis are all kinetochore microtubules the same length
Metaphase
Do cells entering mitosis have the same amount of DNA as cells entering meiosis
yes
True or False: During S phase, the number of chromosomes does NOT change, only their appearance changes
True
What are the two things that occur in Prophase 1
synapsis (formation of tetrads) and crossing over
Why did Mendel use pea pants for his experiment? give 3 reasons
short generation time, their fertilization can be controlled, several easily observed traits
What is a nucelosome?
A complex of 8 core histones and DNA wrapped around them; basic unit of DNA packaging in eukaryotes ONLY
Describe euchromatin vs. heterochromatin
Euchromatin is loosely packed chromatin whose DNA is loosely packed (expressed)= used to make proteins and found in non-dividing cells only,
heterochromatin is tightly packed chromatin whose DNA is tightly packed (not expressed)= can not be used to make proteins; found in dividing cells, and at the centromere and telomeres in both dividng and non-dividing cells
After the DNA is duplicated, what holds the sister chromatids together in each chromosome
cohesin proteins
Explain independent assortment of chromosomes and when does it occur
random orientation of tetrads on the metaphase plate during metaphase 1
In humans, curly hair (B) is dominant over straight hair (b). A curly-haired man marries a straight-haired women and they have three children, two of whom are curly-haired, and one of whom is straight-haired. What are the genotyps of the children?
Bb and bb
Put these steps in order for packaging DNA for cll division: solenoid, rosettes, loop, chromosome, nucleosome
1. nucleosome 2. solenoid 3. chromatin loop 4.rosttes 5. chromosome
What is the purpose of the G2/M checkpoint?
cell assesses success of DNA replication and centrosome duplication, cell makes a commitment to mitosis
At what phase of mitosis are kinetochore microtubules attached to each sister chromatid of the chromosome via kinetochore
Prometaphase
A species with a diploid number of 10 chromosomes has how many different combinations of paternal and maternal chromosomes possible in the offspring?
32 x 32= 1024
What is the phenotypic ratio in a dihybrid cross between 2 heterozygotes?
9:3:3:1
How can you test whether you have a purebred
testcross: cross the individual with unknown genotype (LL or Ll) with a homozygous recessive (ll)
Human skin color, which can range from pale to very dark, follows what kind of pattern?
a. codominance
b. incomplete dominance
c. epistasis
d. pleitropy
e. polygenic inheritance
e. polygenic inheritance