Chapter 8: Inheritance, genes, and chromosmes Flashcards
The “Particulate theory of inheritance” was founded by?
Gregor Mendel
particles = genes
What experiments did Gregor Mendel do?
Breeding experiments with pea plants
Why did Mendel use pea plants?
- Can mate with others(cross-pollinate) or with self (self-pollinate)
- Produce large numbers of offspring
- Fast generation time: time it takes for one seed to grow and yield new seeds
What are the three names of generations? ONLY FOR PLANTS
- P
- F1
- F2
What is a monohybrid cross?
Only one gene invovled
What is a dihybrid cross?
Dihybrid cross is a cross between two individuals with two observed traits that are controlled by two distinct genes.
What is a hybrid cross?
- Mate two different homozygotes to get a heterozygote/hybrid
- Mate the hybrids/heterozygotes
How do you decide which plant is the mother?
Wherever the pollen is moving will be the mother
Which organelles contain their own DNA?
Mitochondria and chloroplasts
DNA outside the nucleus is inherited through the ____(1). This is known as __(2)
(1) mother
(2) cytoplasmic inheritance
Genes are ____(1). Each gene is a small stretch of a ___(2), and ___(2) are made of ___(3).
(1) units of inheritance
(2) Chromsomes
(3) DNA
___(1) are forms of a gene. Each ___(1) is generally either dominant or ___(2).
(1) Allele
(2) Recessive
The __(1) of an organism tell you what genes and alleles it has. An organism with two copies of the same allele is ___(2) while an organism with two different alleles is ___(3)
(1) genotype
(2) homozygous
(3) heterozygous
The ___(1) of an organism tells you what appearance it has.
(1) phenotype
What was mendel’s particulate theory?
The units responsible for inheritance are discrete particles that exist within an organism in pairs and separate during gamete formation.
ALWAYS CHECK IF THE QUESTION SI AKSING TO EXPRESS THE RESULTS OF A PUNNETT SQUARE IN PERCENT, FRACTION, DECIMAL, ETC
RAWR
The law of segregation explains what happens to ___(1). The law of independent assortment explains what happens to ___(2)
(1) a single gene during meiosis
(2) two genes during meiosis
What sis Mendel use to illustrate independent assortment?
a dihybrid cross
Why is the law of independent assortment?
Alleles of different genes assort into gametes independently of each other
What is the law of segregation
T
To determine the probability that two independent events will both happen…..
MULTIPLY the probabilities of the individual events
To determine the probability that one event OR another will happen ….
add the probabilities of the individual events
Human geneticists rely on ___(1). ___(1) show phenotype segregation in several generations of related individuals.
(1) Pedigrees
What five things have we learned since Mendel?
- We cna extend mendel’s principles to study organisms that cannot be self-crossed
- Simple dominance is not always the case
- Most traits result from multiple genes and/or interactions with the environment
- Sometimes, the law of independent assortment is “violated” through linkage and sex linkage
- DNA outside the nucleus is inherited through the mother
What is the wild type?
The usual phenotype
What is the mutant?
unusual phenotype
What is the naming convention for humans?
Generation I, Generation II, Generation III
How do you determine if a trait is dominant or recessive?
Dominant:
- every affected kid has at least 1 affected parent, tends not to skip generations
Recessive:
- Affected kid may gave 2 unaffected parents, trait tends to skip generations
Simple dominance is not always the case. What are the two other types of dominance?
- Incomplete dominance: a blending of the two alleles that results in a third phenotype that doesn’t look like either of the parents.
- Codominance(ex. blood types): both parent phenotypes show up together on the offspring.
What is linkage?
Genes on the same chromosome do not assort independently
Just because two genes are on the same chromosome _____(1) mean they will always be inherited together.
(1) doesn’t
How does distance affect the likelihood that two genes will be inherited together?
Genes that are close together tend to be inherited together. The farther apart on the same chromosome two genes are the more likely the genes will be separated during crossing over/recombination
What does hemizygous mean?
only having one allele, as is the case with male sex-linked chromosomes
What is the trend with sex-linked inheritance?
More males are affected than females.
