Gregor Mendel

1
Gregor Mendel

• Quiz and photos

2
Gregor Mendel was

1. an English scientist who carried out research
   with Charles Darwin
2. a little known Central European monk
3. an early 20th century Dutch biologist who carried
   out genetics research

3
B is CORRECT

• He worked in virtual obscurity during the mid
• 19th century.
• Unfortunately, Charles Darwin did not know of
• Mendels work. He was one of the few
• scientists of that time who might have
• understood and appreciated Mendels huge
• contribution to science.

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Which statement is true about him?

1. His discoveries concerning genetic inheritance
   were generally accepted by the scientific
   community when he published them during the mid
   19th century.
2. He believed that genetic traits of parents will
   usually blend in their children.
3. His ideas about genetics apply equally to plants
   and animals.

5
C is CORRECT

• He gave us the basis for understanding genetic
  inheritance in all living things, including
  humans. His realization that we inherit units or
  genes was the key to it all.

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Mendel believed that the characteristics of pea
plants are determined by the

1. inheritance of units or factors from both parents
2. inheritance of units or factors from one parent
3. relative health of the parent plants at the time
   of pollination

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A is CORRECT

• We now call these units genes. Each inherited
  trait is determined by at least one gene from
  each parent.

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An allele is

1. another word for a gene
2. a homozygous genotype
3. a heterozygous genotype
4. one of several possible forms of a gene

9
D is CORRECT

• An allele is one of two or more alternate forms
  of a gene. If an individual is homozygous (YY or
  GG) for a trait, it has inherited the same allele
  from both parents. If it is heterozygous (YG),
  it has inherited different alleles for the trait.

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Phenotype refers to the

• ______________________ of an individual.
• a) genetic makeup
• b) actual physical appearance
• c) recessive alleles

11
B is CORRECT

• Phenotype is the observable characteristics,
  including physical appearance. It results from
  the genotype and environmental influences. A
  phenotype includes not only easily measured
  traits like hair color but also less apparent
  ones such as blood type.

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When the genotype consists of a dominant and a
recessive allele,

• the phenotype will be like the dominant allele.
• the phenotype will be like the recessive allele.
• the phenotype will be neither like the dominant
  nor the recessive allele.

13
A is Correct

• The dominant allele masks the appearance of the
  recessive one. However, there are some traits
  for which this simple rule of dominance does not
  apply.

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Assuming that both parent plants in the diagram
below are homozygous, why would all of the f1
generation have yellow phenotypes?  

• a) because the f1 genotypes are homozygous
• b) because yellow is dominant over green
• c) because both parents passed on yellow alleles

15
B is correct

• When there is a genotype that consists of a
  dominant and a recessive allele, the phenotype
  generally looks like the dominant one. In this
  case, yellow is dominant.

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The idea that different pairs of alleles are
passed to offspring independently is

• a) Mendel's principle of unit inheritance
• b) Mendel's principle of segregation
• c) Mendel's principle of independent assortment

17
C is Correct

• This is a definition of his principle of
  independent assortment. Stated in other words,
  the genes that determine a trait assort
  independently of the genes for other traits. As a
  result, new combinations of genes, present in
  neither parent, are possible.

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The idea that the pair of alleles of each parent
separate and only one allele from each parent
passes to an offspring

• is Mendel's principle of independent assortment
• b) is Mendel's principle of hybridization
• c) is Mendel's principle of segregation

19
C is correct

• This is the definition of the principle of
  segregation. Stated in other words, genes occur
  in pairs and during the process of sex cell
  production, the members of each pair separate so
  that each sperm and ovum cell receives one member
  of each pair.

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Task Definition of terms

• Pollination
• Unit genes
• Homozygous genotypes
• Heterozygous genotypes
• Allele (dominant and recessive)
• Phenotype
• Independent Assortment
• Segregation
• Hybridization

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Pollination

• the process that transfers pollen grains, which
  contain the male gametes (sperm) to where the
  female gamete(s) are contained within the carpel

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Unit Gene

• A gene is a unit of Heredity

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Allele

• (from the Greek a?????? allelos, meaning each
  other) is one member of a pair or series of
  different forms of a gene. Usually alleles are
  coding sequences.
• An individual's genotype for that gene is the
  set of alleles it happens to possess. In a
  diploid organism, one that has two copies of each
  chromosome, two alleles make up the individual's
  genotype.

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Zygosity

• It refers to the genetic condition of a zygote.
  In genetics,it describes the similarity or
  dissimilarity of DNA between homologous
  chromosomes at a specific allelic position.
• Zygosity is also used to describe the genetic
  condition of the zygote(s) from which twins
  emerge, where it refers to the similarity or
  dissimilarity of the twins' DNA. Identical twins
  are monozygotic - Fraternal twins are dizygotic.

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Zygosity

• The terms homozygous, heterozygous and hemizygous
  are used to simplify the description of the
  genotype of a diploid organism at a single
  genetic locus.
• Diploid organisms generally have two alleles at
  each locus, one allele for each of the two
  homologous chromosomes.
• Homozygous describes two identical alleles or DNA
  sequences at one locus, heterozygous describes
  two different alleles at one locus, and
  hemizygous describes the presence of only a
  single copy of the gene in an otherwise diploid
  organism.

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Homozygous genotypes

• Occurs when both alleles at a particular gene
  locus are the same.

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Heterozygous Genotype

• Occurs when the two alleles at a particular gene
  locus are different. A heterozygous genotype may
  include one normal allele and one mutation, or
  two different mutations. The latter is called a
  compound heterozygote.

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Phenotype

• Any observable characteristic of an organism,
  such as its morphology, development, biochemical
  or physiological properties, or behavior.
  Phenotypes result from the expression of an
  organism's genes as well as the influence of
  environmental factors and possible interactions
  between the two.

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Independent assortment

• Mendel's law of independent assortment, states
  that allele pairs separate independently during
  the formation of gametes. This means that traits
  are transmitted to offspring independently of one
  another.
• Assortment separation into classes

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Segregation

• allele pairs separate or segregate during gamete
  formation, and randomly unite at fertilization
• To segregate to separate or isolate from the
  main body or group

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hybridization

• Production of a hybrid by pairing complementary
  ribonucleic acid and deoxyribonucleic acid (DNA)
  strands. Production of a hybrid by pairing
  complementary DNA single strands