Chapter One: Mendel's Principles of Heredity Flashcards
the study of heredity and the variation of inherited characteristics
genetics
Aristotle believed that gender was determined by ____
semen and menstrual blood which interacted in the womb to direct early development
Aristotle believed that it was the ___ of semen and menstrual blood which determined gender
temperature
Aristotle believed that semen was ___ and menstrual blood was ___
hot
cold
assumed that an entire organism was preformed in sperm or egg and only had to unfold and grow
preformation theory
inheritance believed to be true before Mendel; believed the averaging out of every characteristic
blending inheritance
why is blending inheritance not possible
would make natural selection by evolution impossible
doesn’t explain how siblings can be different
theory that states every part of the body emits gemmules which migrate to the gonads and contribute to the fertilized egg
pangenesis
___ believed pangenesis
Darwin
central dogma of life
DNA transcribes RNA
RNA translates protein
stores and replicates biological information
DNA
an intermediate in the production of proteins
RNA
catalyze biological processes
proteins
another name for a gene
open reading frame “ORF”
genetics explain the mechanism that determine ____
inheritance of traits
genes are the basic units of ___
heredity
region of DNA that encodes a protein or RNA
gene
how many genes code for a protein
about 20,000
the way genes transmit traits from parent to offspring
heredity
purposeful control of mating by choice of parents for the next generation; first applied genetic technique
artificial selection
four general themes of Mendel’s work
- variation is widespread in nature an provides for continuously evolving diversity
- observable variation is essential for following genes from one generation to another
- variation is inherited by genetic laws, which can explain why like begets like and unlike begets unlike
- Mendel’s laws apply to all sexually reproducing organisms
6 reasons why Mendel was successful
- studied pea plants
- examined distinct traits
- used pure-breeding lines
- made reciprocal crosses
- worked with large numbers of plants and quantified data
- black and white experiment system
what is a reciprocal cross
crossing the same two plants but switching the sex; the first cross plant 1 is female and plant 2 is male, the second cross plant 1 is male and plant 2 is female
monohybrid crosses reveal the law of ____
segregation
Mendel proposed that each plant carries ___ of a gene
two copies
gene coding for a fully functional protein
dominant allele
gene coding for a non-functional protein
recessive allele
alternative forms/variations of a gene
allele
individuals with two different alleles for a single trait
monohybrid
there are 64 possible ___ combinations and 20 ___; this means that subtle changes in DNA can cause ____
codon
amino acids
major changes in traits
the law of segregation states that
two alleles for each trait separate during gamete formation
alleles then ___ during fertilization
unite at random
product rule
the product of two independent events occurring together is the product of their individual probabilities
sum rule
probability of either of two mutually exclusive events occurring is the sum of the their individual probabilities
observable characteristic
phenotype
pair of alleles in an individual
genotype
how do you determine the genotype of an individual with a dominant phenotype
testcross (crossing the dominant individual with a homozygous recessive)
if dominant individual is heterozygous, a testcross will reveal ___
a 1:1 dominant:recessive ratio
if dominant individual is homozygous, a testcross will reveal ___
all dominant progeny
probability of two events occurring together, use the ___
product rule
probability of one or another event occurring, use the ___
sum rule
dihybrid crosses reveal the law of ___
independent assortment
an individual that is heterozygous for two genes
dihybrid
how do you produce a dihybrid
cross one parent that is homozygous dominant for both with a parent that is homozygous recessive for both
what is the expected phenotypic ratio of a cross of two dihybrids
9 AB: 3: Ab: 3aB: 1ab
the law of independent assortment states that
alleles of genes assort independently and can appear in any combination in offspring
three factors that contribute to phenotype
- genotype
- actions of other genes and their products
- environmental influences and random developmental effects
how do you find the possible number of gametes
2 to the power of how many genes you’re looking at
for gene pairs, the possible number of phenotypic classes is ___ and the possible number of genotypic classes is ___
2 to the power of number of gene pairs
3 to the power of number of gene pairs
chi squared equation
(observed - expected) squared, then divided by expected
the further the chi squared value is from 0, the ____
less accurate the data is
how to determine degrees of freedom for chi squared table
number of genes minus one
always look at the ___ certainty column on the chi squared table
0.05
if chi squared value is more than the value in the table, ____
the variability is due to something other than chance
inheritance is ___, not blending
particulate
there are ___ of each trait in a germ cell
two copies (alleles)
gametes contain ___ of each trait
one copy (allele)
alleles segregate ___
randomly
alleles are ___ or ___
dominant or recessive
different traits assort ____
independently
proteins have many functions that are related to their ___
form
for pea shape, the dominant allele codes for ___ and the recessive allele codes for ___
starch branching enzyme (Sbe1)
nothing
because the recessive allele does not code for Sbe1, ____ build up, leading to ___ peas
sucrose and unbranched starch
wrinkled
for pea color, the dominant allele codes for ___, which functions to ___, and leads to ___ peas
stay green enzyme (Sgr)
break down chlorophyll
yellow
the recessive allele for pea color codes for ___, the pea is ___ because ___
nothing
green
the chlorophyll is not broken down
a specific ___ encodes for a specific ___, whose activity may affect ___
gene
enzyme (protein)
phenotype
many heritable traits in humans are caused by an interaction of ___
multiple genes
there are about ___ single-gene traits known in humans
6,000
even with single-gene traits, determining inheritance patterns in humans can be tricky. why?
long generation time
small numbers of progeny
no controlled matings
no pure-breeding lines
thalassemia inheritance pattern is ___ and caused by a ___
autosomal recessive
single gene
sickle-cell anemia inheritance pattern is ___ and caused by a ___
autosomal recessive
single gene
cystic fibrosis inheritance pattern is ___ and is caused by a ___
autosomal recessive
single gene
tay-sacks disease inheritance pattern is ___ and is caused by a ___
autosomal recessive
single gene
Huntington disease inheritance pattern is ___ and is caused by a ___
autosomal dominant
single gene
orderly diagrams of a family’s relevant genetic features
pedigrees
pedigrees are used to study ___
inheritance in humans
a horizontal pattern of inheritance indicates a ___ trait
recessive
a vertical pattern of inheritance indicates a ___ trait
dominant
with a dominant trait, every affected person has at least ___
one affected parent
the abnormal Huntington protein ___, even when the normal protein is also present
damages nerve cells
recessive cystic fibrosis allele codes for an abnormal ____
CFTR protein
CFTR protein regulates the passage of ___ across the ___
chloride ions
cell membrane
homozygous recessive CF patients have a build up of ___ inside the ___ and a build up of ___ outside the ___
chloride ions
cell membrane
mucus
cell membrane
three key aspects of pedigrees with dominant traits
- affected children always have at least one affected parent
- as a result, dominant traits show a vertical pattern of inheritance
- two affected parents can produce unaffected children, if both parents are heterozygous
four key aspects of pedigrees with recessive traits
- affected individuals can be the children of two unaffected carriers, particularly as a result of consanguineous matings
- all the children of two affected parents will be affected
- rare recessive traits show a horizontal pattern of inheritance
- recessive traits may show a vertical pattern of inheritance if the trait is extremely common in the population
