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Bio 151. Lecture 20, Simple Patterns of sexual inheritance

Terms in this set (40)

Meiosis is when a diploid cell undergoes 2 divisions to make 4 ____ cells:
Meiosis is when a diploid cell undergoes 2 divisions to make 4 haploid cells
In Meiosis, DNA replicates to make ______ just like mitosis:
sister chromatids
During Meiosis I, homologous chromosomes separate whereas _____ do not separate:
Sister chromatids do stay together
What is another name for the tetrad?
Synapse
What phenomenon can occur during Meiosis I that leads to genetic variability in cells?
Crossing Over
What is crossing over?
When a pair of homologous chromosomes overlap
What is the site of crossing over called?
Chiasma
What is another name for the tetrad or synapse?
Bivalent
Why do we have sexual reproduction in the first place?

Name 3 significant reasons:
1) Increase diversity

2) Allows species to adapt to changing environment (spreads adaptive mutations)

3) intermixes different mutant alleles of different genes
Why don't animals just perform asexual reproduction?
Disadvantageous in changing environment
Can bacteria also exchange genetic information?
Yes, they can
How do bacteria undergo genetic change? Name two ways
1) Transformation

2) Conjugation
What is transformation in the context of bacterial genetics?
When DNA fragments embed themselves into the circular DNA of Bacteria
What is conjugation in the context of bacterial genetics?
When long extensions of bacteria membrane extend to other bacteria and transfer fragments of DNA
What is the name of the extensions that bacteria use in conjugation?
Pili
During conjugation of bacteria, are chromosomes passed of fragments of DNA?
Fragments of DNA or small circular plasmids
What are small circular fragments that bacteria pass to other bacteria?
Circular Plasmids
Why did Gregor Mendel use pea plants?

4 Reasons:
1) fast reproduction

2) visible traits

3) Maintain true bred parents

4) Many seeds produced
Pea plants self ______ ?
self-pollinate
What part of the plant produces pollen?
Stamen
What do stamens produce?
pollen (1n male gametes)
What do ovules do?
produce ovules (1n female gametes)
What did Mendel remove from the pea plants?

How did he pollinate the plant?
1) He removed the stamens

2) He cross pollinated the plant with a brush
Mendel noticed that the ______ was not the same as the ____ of the pea plants
The Phenotype was not the same as the Genotype
What is a phenotype?
physical appearance
What is the genotype?
The genetic information of an organism that can be passed on to the offspring
What is the parent generation called in mendelian genetics?
P generation
What is the first generation called in Mendelian genetics?
F1
What is the second generation called in Mendelian genetics?
F2
A genotype of a zygote can be either _____ or _____
Homozygous or Heterozygous
What is a Homozygous genotype?
When both alleles on both homologues are identical (or close enough)
What is a Heterozygous genotype?
When the alleles on homologues are different
What alleles control the phenotype?
Dominant Alleles
What alleles control the phenotype if both homologues have the same or similar alleles?
recessive alleles
Explain Mendel's Law of Segregation
The two alleles in the parent separate from each-other during the formation of gametes
Mendel used probabilities to prove their were two alleles, but there was one problem with this.
Mendel needed large samples to prove there were two alleles
How did he determine what genotype a purple flower was?
He did a "test cross" with itself
What is a test cross and what did Mendel use it for?
A test cross breeds two F1 offspring to determine what the genotype of the F1 is.
When is a pedigree used?
When the phenotypes or known, but the mode of inheritance is not unknown
What happens when you follow two genes at the same time, what is this cross called?
A dihybrid cross
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