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61 Cards in this Set
- Front
- Back
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what is the study on heredity and variation?
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genetics
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what is heredity?
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heredity is the transfer of properties from one generation to the next
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who began breeding peas in his monastery garden to try to deduce heritability in 1857?
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Gregor Mendel
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why did Mendel choose to study pea plants?
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-hybrids could be produced
-many pea varieties were available -peas were small and easy to grow -peas can self-fertilize or be cross-fertilized |
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why are humans bad for researching genetics?
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-generation time is too long
-parents produce few offspring -breeding experiments are unacceptable |
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what was developed several
decades before the first chromosome was seen let alone understood? |
Mendel’s theories
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what is an inheritable unit that can be passed
on to offspring to determine their makeup? |
we call it a gene
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The heritable feature is called what?
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character
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Variants of the character are
called? |
traits
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The genetic counterpart for the character is what?
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the gene
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The variants of a gene is called what?
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alleles
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the Gene is = to what?
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character (flower color)
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the Allele is = to what?
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trait (purple or white)
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Each gene is a section of (blank) that codes
for a (blank)... |
DNA; protein
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A gene’s (blank) is its “address” on a chromosome
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locus
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Plants and animals have two sets of the same DNA.. this term refers to what?
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diplod
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Diploid organisms have two copies of each (blank)?
(one from mother, one from father) |
chromosome
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Each pair of chromosome from the parents are called what?
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homologous chromosomes
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Alleles of a particular gene can be (blank) if it is written as BIG LETTER?
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dominant
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What is written as a small
letter in relation to each other? |
codominant or recessive
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Name the 3 generations Mendel tracked certain characters for...
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P generation (parents)
F1 generation (first offspring) F2 generation (offspring of F1) |
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The ratio of the F2 generation can help to
determine what? |
which allele is dominant
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One way to deduce the possible combinations is to use what?
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use a Punnett square
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what is based off of the alleles in a diploid organism?
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Homozygous- same allele
Homozygous dominant or homozygous recessive Heterozygous- different allele |
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same allele
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homozygous (recessive or dominant)
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waht is Phenotype?
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it is what you see in the plant, its traits
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what is Genotype?
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it is the genetic makeup of the
plant, its alleles |
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What is a way to deduce the possible combinations?
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use a Punnett square
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The ratio of what generation can help to determine which allele is dominant?
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the F2
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If the genotype is unknown, you can perform a test cross with a ...?
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known homozygous recessive
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what is the Principle of Segregation?
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Two copies of a gene separate (segregate) during
meiosis to form gametes Gametes are rejoined at random during fertilization |
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what are you looking at on a monohybrid cross?
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looking at a single character
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what are you looking at on a dihybrid cross?
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two different characters (genes) at the
same time |
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what is the Principle of Independent Assortment?
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-In a dihybrid cross, the alleles of each gene
assort independently -this applies only to genes on different, non-homologous chromosomes -Genes located on the same chromosome tend to be inherited together |
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what do Genetic differences in
cells arise from? |
-crossing over
-random alignment of homologues in metaphase I (independent assortment) -Random fusion of gametes |
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Mendel’s principles of segregation and
independent assortment |
When tossing a coin, the outcome of one toss
has no impact on the outcome of the next toss |
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inheritance patters
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Beyond two genes, Punnett squares
become impractical to use to determine |
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determine the chances using fractions
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Using the rules of probability can..?
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Rule of addition
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-the probability of 2 mutually exclusive events
occurring simultaneously is the sum of their individual probabilities -When crossing Pp x Pp, the probability of producing Pp offspring is -probability of obtaining Pp (1/4), PLUS probability of obtaining pP (1/4) - ¼ + ¼ = ½ |
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Rule of multiplication
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- the probability of 2 independent events
occurring simultaneously is the PRODUCT of their individual probabilities. -When crossing RrYy x RrYy, the probability of obtaining rryy offspring is: - probability of obtaing rr = ¼ - probability of obtaining yy = ¼ probability of rryy = ¼ x ¼ = 1/16 |
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Mendel’s model of inheritance assumes
that: |
- each trait is controlled by a single gene
- each gene has only 2 alleles - there is a clear dominant-recessive relationship between the alleles Most genes do not meet these criteria |
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Some examples of single gene traits:
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Earlobe attachment
Widows peak Hitch hiker’s thumb |
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The phenotype of a trait
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an accumulation of
contributions by multiple genes. |
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Examples: human height and skin color
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These traits show continuous variation and are referred to as quantitative traits
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multiple genes are involved in controlling
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Polygenic inheritance occurs when
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Pleiotropy refers to
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an allele which has more
than one effect on the phenotype |
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Pleiotropy
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This can be seen in
human diseases such as cystic fibrosis or sickle cell anemia -In these diseases, multiple symptoms can be traced back to one defective allele |
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Incomplete dominance
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the heterozygote is intermediate in phenotype
between the two homozygotes |
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Codominance
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the heterozygote shows some
aspect of the phenotypes of both homozygotes For example, the four phenotypes of the ABO blood group in humans: three alleles for the enzyme (I) that attach to A or B carbohydrates to red blood cells |
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Dominant alleles are not
necessarily more common in populations than recessive alleles |
one baby out of 400 in the United States is
born with extra fingers or toes 6 digits is dominant |
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character depends on environment as well
as genotype ------------------------------------ hydrangea flowers of the same genotype range from blue-violet to pink, depending on soil acidity pigment production in Himalayan rabbits and Siamese cats only occurs at temperatures below 30oC |
Another departure from Mendelian genetics arises when the phenotype for a
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and children
across generations |
A pedigree is a family tree that describes
the relationships of parents and ... |
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pedigrees
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Inheritance patterns of particular traits can be
traced and described using |
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predictions about future offspring
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Pedigrees (along with Punnett squares or
probability) can also be used to make ... |
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inherited, dominant and
recessive |
Many disorders are ...
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to suffer from the disorder(Albinism, Sickle cell anemia, cystic fibrosis)
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An individual must be recessive homozygous to ...
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-Carriers are heterozygous
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-They carry the recessive allele but are
phenotypically normal |
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are rare and arise by mutation
Examples: Achondroplasia is a form of dwarfism Huntington’s disease is a degenerative disease of the nervous system |
-Dominant alleles that cause lethal disease
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Pedigree evaluation and genetic testing
(Fetal testing) |
what informs parents of the risk of passing on a disease?
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genetic information on a fetus during pregnancy
(Newborn screening) |
Amniocentesis and chorionic villus sampling can
provide |
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birth by simple tests
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Some genetic disorders can be detected at ...
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