Genetics Study Guide Flashcards
What is meiosis?
A type of cell division that produces reproductive cells (gametes/sex cells) with half the number of chromosomes (haploid)
What type of cells does meiosis occur in?
Sex cells (gametes)
What is crossing over?
The exchange of genetic information between homologous pairs of chromosomes
What stage of meiosis does crossing over occur?
Prophase I
What are some differences and similarities between mitosis and meiosis
- Mitosis and meiosis are both forms of cell division
- Mitosis produces 2 daughter cells
- exact copies of the original cell (somatic)
- 46 chromosomes (diploid cells)
- Meiosis produces 4 daughter cells
- sex cells (gametes)
- 23 chromosomes (haploid)
Mendel’s Three Laws of Genetics
- Law of Segregation
- Law of Dominance
- Law of Independent Assortment
The Law of Dominance states:
certain alleles can be more powerful than others
- dominant alleles always show their traits
- recessive alleles only shown when no dominant allele is present
The Law of Segregation states:
only one of the two alleles is transferred to a sperm or an egg
- each gamete carries only one allele for each gene
- two alleles, one allele from each parent (ex: PARENT: Tt
GAMETE 1: T
GAMETE 2: t)
The Law of Independent Assortment states:
the alleles of two (or more) different genes get sorted into gametes independently from one another
Ex: flower color and height.
For example, if you’re looking at two traits, like flower color and plant height, the gene for flower color will assort independently from the gene for plant height when the gametes are formed.
Flower color: C
Plant height: H
They are not inherited differently or dependent on each other.
How many alleles do you have for each trait?
When do these alleles separate?
2; Anaphase I
Some advantages of using pea plants for genetics experiments:
- Reproduce quickly
- Produce many offspring
- Easily identifiable traits
Possible Genotype(s) for Blood Types (ALL)
A: AA, Ai
B: BB, Bi
AB: AB
O: ii
Possible Genotype(s) for Blood Type A
AA, Ai
Possible Genotype(s) for Blood Type B
BB, Bi
Possible Genotype(s) for Blood Type AB
AB
Possible Genotype(s) for Blood Type O
ii
What genotype represents a male
XY
What genotype represents a female
XX
How does gel electrophoresis work
separates the molecules (like DNA) by size
- samples loaded into a gel (agarose)
- DNA placed into wells
- electric current applied (DNA is negative, moves to positive side)
- restriction enzymes cut DNA into tiny pieces
- smaller ones faster
- use DNA bands to compare how closely related two organisms are
What is epigenetics
the science of how genes change from environmental factors
What is CRISPR
a laboratory method of gene editing, making a change to specific bases in DNA
What is Sickle Cell Disease
a single gene disorder caused by a genetic variation (mutation) in the beta-globin gene, causing the cell to be sickle shaped
- beta-globin codes for a protein that’s part of hemoglobin
- a small genetic change occurs in the beta-globin gene which changes the protein, resulting in ‘sickle’ shaped red blood cells
What is Sickle Cell Disease caused by
a genetic variation (mutation) in the beta-globin gene
- beta-globin codes for a protein that’s part of hemoglobin
- a small genetic change occurs in the beta-globin gene which changes the protein, resulting in ‘sickle’ shaped red blood cells
Do 1 sample problem
*Be prepared to read a pedigree and predict the genotypes of the individuals in the pedigree.
Do 1 sample problem
*Be prepared to complete all types of Punnett Squares found in your packet.
VOCAB: genotype
combination of an organism’s alleles
VOCAB: genes
segment of DNA that determines an organism’s trait
VOCAB: recessive
allele that is only expressed when no dominant allele is present
VOCAB: phenotype
physical characteristic of an organism
VOCAB: cross
organisms mate; produce offspring
VOCAB: homozygous
two of the same alleles; purebred
VOCAB: dominant
allele that will always be expressed if present in an organism
VOCAB: alleles
Variations of genes; tall and short, etc
VOCAB: heterozygous
two different alleles; hybrid
VOCAB: gametes
sex cells (sperm and egg)
2 different types of cells
somatic and germ
VOCAB: diploid
a cell containing two sets of chromosomes (46)
ex: skin cell
VOCAB: haploid
a cell containing 23 chromosomes (half of diploid)
”hap”=half
VOCAB: homologous chromosomes
chromosomes that have the genes for the same traits
How many cells does meiosis create?
4
How many cells does mitosis create?
2
VOCAB: pedigree
a family tree that can be used to track genetic traits through a family
VOCAB: tetrad
A pair of homologous chromosomes that have been paired in the cell
