Genetics The Science of Heredity

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Genetics The Science of Heredity
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Unit Vocabulary
Heredity
Passing of traits from parent to offspring.
Traits
Different physical characteristics
Genes
Factors that control traits.
Different forms of a gene. Always two for each
trait. One from each parent.
Alleles
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Alleles
Dominant Allele
Recessive Allele

• The trait that is always exhibited or shows up.
• (Tt) Heterozygous two different alleles for a
  trait
• (hybrid)
• Homozygous two identical alleles for a trait
  (purebred)

The trait that is masked or covered up when a
dominant allele is present. A recessive allele
will show up only if there are two recessive
alleles (tt) (ss) Homozygous 2 identical
recessive alleles (tt) (ss)
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Monohybrid
Dihybrid
A dihybrid is produced by crossing parents that
are heterozygous for two alleles, so that each
gene is represented by two different forms of
alleles. (Tt)
A hybrid produced by crossing parents that are
homozygous for two alleles. (TT) (tt)
Phenotype The physical appearance or visible
traits (green eyes, brown hair, shape of
face) Genotype The genetic makeup or allele
combinations (Tt, TT, tt) Symbolic
representation
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Co dominance - a cross between organisms with
two different phenotypes produces offspring with
a third phenotype in which both of the parental
traits appear together. (chicken with white and
black feathers) Incomplete Dominance -
a cross between organisms with two different
phenotypes produces offspring with a third
phenotype that is a blending of the parental
traits. (flower - white and red pink)
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Punnett Square - is a chart that is used to show
possible combinations of a genetic cross, and to
determine the probability of a particular
outcome. created by geneticist named
Reginald Punnett
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Mendelian GeneticsGregor Mendel (1822
1884) was an Austrian monk whose studies of the
inheritance of traits in pea plants helped to lay
the foundation for the later development of the
field of genetics. He is often called the "father
of genetics." His studies showed that there was
particulate inheritance of traits according to
basic laws of inheritance. The significance of
Mendel's work was not recognized until the turn
of the twentieth century.Living as a monk, he
raised and monitored more than 20,000 pea plants
inside the walls of his monastery.
Particulate inheritance - traits that
insures a species survival.
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Mendels Pea Plant Experiments

• Mendels 1st Experiments
• Mendel used purebred plants PP, pp
• PP for all purple flowers and tt for white
  flowers
• He called the offspring from each cross First/F1
  Generation plants
• Each of the offspring had purple flowers with an
  heterozygous allele combination Pp
• Mendels 2nd Experiment
• Mendel allowed the first generation to
  self-pollinate
• The white flower reappeared.
• 31 Ratio

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Probability

• Probability - (or likelihood) is a measure or
  estimation of how likely it is that something
  will happen.
• Probability is often written as a fraction or a
  percentage.
• If you flip a coin the probability of flipping
  heads is 50 or ½.

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Meiosis

• Meiosis 1
• At the end of Meiosis 1 there are two daughter
  cells with a full set of chromosomes that are
  identical to the parent cell.
• The two cells are called daughter cells.

• During meiosis II the chromosomes are not
  copied
• Four (sex cells) called gametes are produced.
  Egg cells for females and sperm cell for males.
• Each gamete has half the number of chromosomes
  than the original cell.

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Mitosis Vs. Meiosis

• Cell division for reproduction
• One large cell will produce four smaller cells
  called gametes. Each cell will have half the
  normal number of chromosomes.
• DNA does not duplicate during meiosis 2.
• Cells produced will fuse together during sexual
  reproduction.
• The egg cell and sperm cell will combine
  (fertilization) to form zygote (new organism)
  with a complete set of chromosomes.

• One large cell makes two smaller cells with same
  number of chromosomes allows organisms to grow,
  develop and repair.
• Before Mitosis begins the chromosomes copy
  themselves.
• The two new cells are called daughter cells.
• Both new daughter cell have a full set of
  chromosomes.

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• DNA - DEOXYRIBONUCLEIC ACID
• The double helix model was discovered by a group
  of scientists named Watson, Crick and Franklin
• The steps of the double helix is made of
  nucleotides.
• Four nitrogen bases Adenine always pairs with
  Thymine (AT) and Guanine always pairs with
  Cytosine (GC)
• Alternating bands of sugar and phosphates make
  up the sides of the double helix.

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DNA Continued
Humans sex cells normally have 23 pairs of
chromosomes, for a total of 46 after the egg cell
and sperm cell combine. Twenty-two of these
pairs, called autosomes, look the same in both
males and females. The 23rd pair is called the
sex chromosomes and differs between males and
females. Females have two copies of the X
chromosome or XX, while males have one X and one
Y chromosome. DNA lies within the nucleus of all
cells in humans and other living organisms. Most
of the DNA is placed within the nucleus and is
called nuclear DNA. However, a small portion of
DNA can also be found in the mitochondria and is
called mitochondrial DNA or mtDNA.

• DNA stores all the genetic information for an
  organism, and it can replicate itself and be
  transmitted to all the organism's offspring.
• DNA is located in the nuclei of cells, which make
  up the body.
• DNA can be considered one of the building blocks
  of the body.
• Genes are hereditary material that lies within
  the cell nucleus. Genes, which are made up of
  DNA, act as instructions to make molecules called
  proteins.

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The DNA can make copies of itself. Both the
strands of the DNA open up and make a copy of
each and become two DNA stands. DNA consists of
2 strands in a twisted ladder structure called
the Double Helix.

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Karyotype A picture of all the chromosomes in a
cell lined in pairs.
Female
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Male
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Pedigrees

• Pedigrees are one tool that geneticists use to
  trace the inheritance of traits in humans.
• A pedigree chart or family tree that tracks
  which members of a family have a particular
  trait.
• The trait recorded in a pedigree can be for an
  ordinary trait such as a widows peak, or it could
  be a sex link traits such as color blindness or
  hemophilia.

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Hemophilia
Hemophilia is the name of a genetic disorder
which means the body's inability to control
bleeding. It is called a sex linked disorder
because it is carried on the x chromosome.
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Color Blindness
The charts below show the most common types of
color blindness. If a certain pigment is missing
in your eyes, you may have trouble seeing
blue-yellow colors. People with blue-yellow color
blindness usually have problems identifying reds
and greens, too.
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Mutations
Deletion a base pair is left out. Insertion
an extra base is added Substitution - the wrong
base is used. (most common)
A genetic disorder is an abnormal condition that
a person inherits through genes or chromosomes.
Some occur in sex cells during meiosis, and are
passed down from the parents cells. These
abnormal conditions are called mutations. There
are three types of mutations.
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Genetic Disorders
This adorable child has a genetic disorder called
down syndrome. A person with down syndrome
has an extra copy of chromosome 21. The extra
chromosome is the result of an error made during
meiosis. People with down syndrome have a
distinctive physical appearance and some degree
of mental or cognitive problems. Heart defects
are also common but can be treated.
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• Klinefelter syndrome is a disorder that affects
  only males. Males normally have an X chromosome
  and a Y chromosome (XY). But males who have
  Klinefelter syndrome have an extra X chromosome
  (XXY), This called an insertian giving them a
  total of 47 instead of the normal 46 chromosomes.
• People with this disorder develop as males with
  subtle characteristics that become apparent
  during puberty. They are often tall and usually
  don't develop secondary sex characteristics, such
  as facial hair or underarm. The extra X
  chromosome primarily affects the testes, which
  produce sperm cells and the male hormone
  testosterone.

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Genetic Disorders cont.

• Turner Syndrome
• Normally, females inherit one X chromosome from
  their mother and one X chromosome from their
  father. But females who have Turner syndrome are
  missing one of their X chromosomes. (omission)
• Women with Turner syndrome are usually sterile
  and cannot have children.

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Other Genetic Disorders

• Albinism is a congenital disorder in which there
  is little or completely no production of melanin
  in hair, skin and iris of the eyes. Hence people
  suffering from albinism have light-colored skin,
  hair and eyes.
• Color Blindness - refers to the inability to
  differentiate among certain colors. Color
  blindness is most commonly the result of
  mutations in the X chromosome. However, research
  has shown that mutation in 19 different
  chromosomes can cause color blindness.
• Cystic Fibrosis - is an inherited disease of the
  glands that secrete mucus and sweat. Cystic
  fibrosis causes the mucus to become thick,
  sticky. The mucus clogs various organs of the
  body, that results in other complications. It
  mostly affects lungs, liver, pancreas, sinuses,
  intestines and sex organs. At present, there is
  no cure for cystic fibrosis.

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• Hemophilia is the name of a genetic disorders
  which mean the body's inability to control
  bleeding. The bleeding might be exterior, if the
  skin is broken by a cut, scrape, or abrasion, or
  it can be interior, into joints, muscles, or
  organs which are hollow. The result can be
  visible on the skin or subtle (e.g., brain
  bleeding).
• Muscular Dystrophy is a genetically inherited
  disorders of progressive degeneration of skeletal
  muscles. It also causes defects in muscle
  proteins and death of muscle cells and tissues.
  These disorders vary in severity and the extent
  and distribution of muscle weakness. Although the
  skeletal muscles are primarily affected, muscular
  dystrophy may impair functions of other systems
  of the body as well.
• Sickle cell disease or sickle cell anemia is a
  blood disorder. A mutation causes sickling of the
  red blood cells that may lead to a number of
  complications.

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Genetic Counseling
If a couple has a family history or concern about
a genetic disorder they may seek help from a
genetic counselor. Genetic counselors help
couples understand their chances of having a
child with a particular genetic disorder. They
use tools such as karyotyping, pedigree charts
and Punnett squares to help them in their work.
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Genetic Engineering
Genetic engineering is sometimes called gene
splicing because a DNA molecule is cut open and
a gene from another organism is spliced into it.
Genetic engineering can improve medicines,
improve food crops, and may cure many human
genetic disorders.
In the last few decades geneticists have
developed a powerful technique for producing
organisms with desired traits. This process is
called genetic engineering. In genetic
engineering genetic information is transferred
from one organism to another organism.
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Genetic Engineering in Bacteria
Researchers had their first success with genetic
engineering when they inserted DNA from another
organism into bacteria. Once the DNA is spliced
into the bacteria, for example, insulin all of
that bacteria's offspring will contain this
human gene. In this case the human code for
insulin.
Why are bacteria used for gene splicing?
Because bacteria reproduce quickly, and large
amounts of insulin can be produced in a short
amount of time. Then the insulin can be
collected and used to treat people with
diabetes.
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Gene Therapy
This process involves inserting working copies
of a gene directly into the cells of a person
with a genetic disorder. For example, people
with cystic fibrosis do not produce a protein
that is needed for proper lung function. With
gene therapy scientists can insert copies of the
gene into the harmless virus. The engineered
virus can then be sprayed into the lungs of
patients with cystic fibrosis.
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Selective BreedingTheir are two types of
selective breeding called inbreeding and
hybridization
Inbreeding Inbreeding involves cross breeding
two individuals that have identical or similar
sets of alleles. As a result organisms have
offspring that are very similar to those of their
parents. For example, breeders produce pure
breed dogs such as golden retrievers and other
dog breeds.
Unfortunately, because of inbreeding the
offspring have a greater chance of inheriting
alleles that lead to genetic disorders such as
hip problems, cataracts and certain types of
cancers.
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Hybridization
Hybridization breeders cross two genetically
different individuals. The hybrid organism that
results is bred to have the best traits from both
parents. For example, a farmer might cross corn
that produces many kernels with corn that is
resistant to disease. The result is corn plants
with both of the desired traits. Today, most
crops grown on farms and in gardens were produced
by hybridization.
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Cloning
A clone is an organism that is identical to the
organism from which it was produced. This means
that a clone has exactly the same genes as the
organism from which it was produced.
Cloning Plants A cutting is one way to clone a
plant. A small stem or leaf is cut from a plant
and an entire new plant will grow. The new plant
will be identical to the plant is was cut from.
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• Cloning Animals Dolly was the first clone of an
  adult mammal ever produced. To create Dolly
  scientists followed these steps
• First researcher removed an egg cell from one
  sheep.
• Second the cells nucleus was replaced with the
  nucleus from a six year old sheep.
• Third the egg was then implanted into the
  uterus of a third sheep.
• Five months later Dolly was born. Dolly was
  genetically identical to the six year old sheep
  that supplied the nucleus.

Since Dolly, scientist have cloned pigs and
calves. Scientists hope that cloning animals
will help humans live healthier lives. For
example, pigs that are being cloned have genes
the will make their organs suitable for organ
transplant into humans.
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Biotechnology
Biotechnology is the use of biological processes,
organisms, or systems to manufacture products
intended to improve the quality of human life.
A few examples of modern biotechnology are
tissue cultures, genetic engineering, recombinant
DNA techniques, mutagenesis, drugs, antibiotics,
antibodies, pesticide free crops, breeding ,
hybridization, and cloning.
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Bioethics
Bioethics is a group of principles that help
people determine what is right and what is wrong
in biological and medical investigations. When
scientist conduct investigations they follow
these guidelines In the laboratory they must
follow all safety instructions and wear safety
equipment. In the field they must respect all
living organisms, their habitats and their
environment. During any testing with humans or
animals, subjects should not be harmed
unnecessarily. Human test subjects should be
informed of possible consequences of the test
before they agree to take part. Lastly, all
subjects should be treated humanly.
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Sexual and Asexual Reproduction

• Sexual Reproduction - Reproduction that
  involves two parents.
• Asexual Reproduction Reproduction that involves
  one parent.

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Reproduction of Bacteria

• Bacteria When bacteria are living in the
  suitable conditions (lots of food, stable
  temperature) they can reproduce every 20
  minutes.
• Binary Fission (asexual) a type of reproduction
  in which one cell divides into two identical
  cells.
• Conjugation (sexual) one bacterium transfers
  some of its genetic material into another
  bacterial cell through a thin, thread-like bridge
  that joins the two cells.
• Conjugation results in bacteria with a new
  combination of genetic material.

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Reproduction in Protist

• Protist also reproduce through binary fission
  (asexual) and multiple fission to make more than
  two offsprings from one parent
• Conjugation (sexual)are in single cell organisms.

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Reproduction in Fungus

• Sexual or Asexual
• Asexual Reproduction 2 ways
• The hyphae break apart and each new piece becomes
  a new fungus.
• Production of spores - spores are small
  reproductive cells that are protected by a thick
  cell wall. Spores are light and can spread by
  the wind. When conditions are right the spore
  will grow into a fungus.
• Sexual Reproduction happen when special
  structures form to make sex cells. The sex cells
  join to produce sexual spores that grow into new
  cells.

Hyphae are threadlike filaments made of cells
that have openings that allow cytoplasm to move
freely between cells.
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Reproduction in Plants
Stamens the male reproductive parts where pollen
is produced . Pistils the female reproductive
parts . The base of the pistil contains ovary
which has one or more ovules. First pollen falls
on a stigma. Next the sperm cell and the egg
cell join together in the flower ovule. The
zygote develops into the embryo part of the seed.
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Reproduction in Animals

• Invertebrates
• Fragmentation - In this type of reproduction,
  the body of the parent breaks into distinct
  pieces, each of which can produce an offspring.
  Planarians exhibit this type of reproduction.
• Regeneration - In regeneration, if a piece of a
  parent is detached, it can grow and develop into
  a completely new individual. Echinoderms exhibit
  this type of reproduction. (starfish, worms)
• Budding when part of an organism breaks off and
  forms a new organism (hydra, sponge)

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Vertebrates

• Sexual Reproduction Two parents.
• Internal Reproduction Egg cell and sperm cell
  fertilize inside the organism. ex, humans, cats,
  dogs and manatees.
• External Reproduction Egg cell and sperm
  fertilize outside of the organism
• ex. amphibians and fish.

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Advantages and Disadvantages of Asexual and
Sexual Reproduction

• Asexual
• Asexual reproduction does not require any meeting
  of two gametes which means that it can reproduce
  many individuals very quickly.
• But with this it means that there will be very
  little variations in the offspring.
• Asexual reproduction contain the identical
  genetic information from their parents as they
  are essentially a clone.
• Less energy required for reproduction.

• Sexual
• With sexual reproduction there are lots of
  variations because they have a different cell
  from each parent.
• Sexual reproduction is very slow.
• Purges the species of mutations. Since most
  mutations.
• Less population growth
• Requires long-term energy use