Download Chapter 2- Genetics

SCIENCE 30
UNIT A: MAINTAINING HEALTH
Chapter 2- Genetics
Mrs. Steinbrenner
Name:
Chapter 2- Genetics
2.1- What is Genetics?
 Inside the cells of the body there is a ____________ with chromosomes.
 Chromosomes carry _____________, units of heredity.
 Each chromosome contains many different genes.
 Humans have ____ sets of chromosomes (46 in total).
 ____________comes from each parent.
1. Chromosomes
 Long, thin strands of DNA that are coiled around protein molecules for protection.
 Seen at cell division.
 _____ shape is created when copies attach at one point.
2. Genes
 A segment of DNA that codes for a ________ __________________.
 The ____________of the pattern codes for a specific trait (e.g.. Tongue rolling).
 Some genes are dominant (occur more often) and some are recessive.
 _____________ is the study of how parent genes determine the
characteristics of the child.
3. Human Karyotype
 All of the chromosomes matched to their pair is a
____________________.
 3 features are used to identify pairs:
 Length of chromosome (_______________= #1)
 Pattern of dark bands on chromosome.
 Position of centre connection (________________).
 The last 2 chromosomes are the sex chromosomes:
 2 ‘x’ = _________________
 1 ‘x’ and 1 ‘y’ = ________________
 23 chromosomes from ___ is matched by 23 chromosomes from
_____.
▪ Paired chromosomes are ________________
chromosomes
▪ homologous = same information
▪ Similar in ________________ __________________________
 Genetic recombination explains diversity of people.
4. Role of Proteins
 Each gene makes a protein…these are used for/as:
 ___________________ (amylase- digestion).
 Structural (Keratin/ collagen).
 Transport ( cell membranes).
 Hormones (insulin).
 _____________________ (antibodies).
 Energy (Casein).
 Muscle contraction (Actin and myosin).
5. Chromosome replication
 The 2 ways that an exact copy of the DNA from the chromosome is created are:
 Mitosis (_________ reproduction).
 Meiosis (___________ reproduction)
a) Mitosis
 Body cells (_____________________) divide by replicating all the parts and dividing into 2
identical cells (skin, hair, fingernails…).
 A copy of the DNA must be made before replication; each strand replicates and attaches at a
centre point (______________).
 Original 2 strands of DNA (1 from each parent) = ____ strands (2 from each parent).
 2 chromosomes line up at centre of cell (_____________) and are pulled apart.
 Cell membrane splits and 2 new “_________” cells are created.
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“daughter” cell is ___________ to parent (both are diploid(____) cells = pair of homologous
chromosomes).
 Plants undergo mitosis = asexual reproduction.
b) Meiosis
 Reproductive cells (____________) are used to reproduce sexually.
 In humans = sperm (male) and egg (female).
 Create _____________ offspring.
 Starts the same as mitosis
 Cells reproduce chromosomes.
 Homologous chromosomes _______________________________ (Cross over).
 Crossing over
 creates completely new combinations of traits in next generation
 DNA material is exchanged between parent strands = ______________________.
 After crossing over, chromosomes align at equator, divide into 2 separate cells.
 Those 2 cells each divide into 2; ___ cells are produced, each with 23 chromosomes (___).
 Gametes (daughter cells) are ___________ cells because they have ½ the DNA of parent cell.
 Sexual reproduction allows us to maintain both genetic similarity & differences.
Mitosis vs Meiosis
 Mitosis
 ___ division
 daughter cells genetically ________to
parent cell
 produces 2 cells
 2n ________
 produces cells for growth & repair
 no crossing over
 Meiosis
 2 divisions
 daughter cells genetically
___________from parent
 produces __________
 2n  1n
 produces ____________
 crossing over
7. Fertilization
 The sperm and the egg (gametes) are each __________, the fertilized egg is ___________ and can
reproduce through mitosis.
 This increases variation and allows for more than ______________ gene combinations.
 Crossing over improves the variation possible in the gametes; explains why 2 siblings look so
different.
8. Selective Breeding
 Used to improve domestic varieties of plants and animals
 Plants: _________________________
• Sweet, full-kernel corn
• Canola - can germinate and grow rapidly in colder climates
 Purebred or thoroughbred dogs and horses
• _________________- in which similar phenotypes are selected for breeding
 New varieties of plants and animals can be developed by _____________________________.
• Opposite to that of inbreeding
• Blend desirable but different traits
 Corn : Hybrids tend to be more vigorous than either parent
9. Inheritance Ideas
 Prior to the 19th century, __________________ theory was prevalent- body parts developed from
fully formed, tiny parts.
 Charles Darwin theorized evolution and the idea of inherited characteristics; there was no
explanation for how this happened though!

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a) Gregor Mendel: “ ______________________”
 Gregor (1822-1884) Mendel’s work with garden peas provided missing piece in theory of
evolution by natural selection.
 Noticed that traits were not blended but instead one was ____________________.
 Cross-pollination: Transferring ______________ between genetically different plants.
 Mendel discovered that some traits were easy to recognize and studied these.
Mendel’s Experiments
 Factors controlled traits of a plant = ____________.
 A trait can disappear in the 1st generation but reappear in_____of the second generation.
 Some genes were dominant
 Dominant allele – fully expressed physically; ___________________
______________________.
 Other genes were recessive
 Recessive allele – completely masked physically by dominant gene.
Mendel’s Laws
1. Inherited characteristics are controlled by genes that occur in pairs; each gamete receives 1 gene
(_________________).
2. Principal of dominance- 1 gene masks the effect of the other.
1. Dominant trait = ____________
2. _______________ trait = lowercase letter
3. Individuals ______________ genes from parents.
4.______________ inheritance of traits to offspring- not linked to other traits.
2.2- Inheritance
 Inherited traits are passed on to offspring via genes.
 __________________________
 _______________ traits are created by the environment; not genes.
 Scars, ability to speak languages…
a) Alleles
 An _______________ form of a gene responsible for a trait (e.g. Tongue rolling).
 Individuals have __ alleles for every trait located on chromosomes.
 When the chromosomes separate during meiosis, __ allele is passed to each gamete.
Dominance Theory
 2 alleles: ______________________________.
 Dominant alleles are able to mask recessive alleles; result in a dominant trait.
 Recessive traits are coded only when an offspring receives ___________________.
Genetic Terms
 Homozygous: two identical copies of an allele (eg. pp or PP) (“pure”).
 Can be homozygous _____________________
 Heterozygous: ___________________copies of an allele (eg. pP) (“hybrid/carrier”).
 Genotype: the___________ that an individual has.
 Phenotype: the observable ___________ of an individual.
b) Punnett Squares
 If alleles are known, it is possible to predict the ________________.
 Punnett squares are used to simplify the process.
 3 steps to use:
 Draw a____________and label each row with alleles
of the ____________.
 Fill in the squares with the genotype.
 Determine the _____________of the offspring with
each genotype.
Phenotype vs. Genotype
 Genotype needs to be described as:
_____________________________________
 Phenotypic ratios are usually expressed as:
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c) Blood Type
 Controlled by 3 alleles:
 A, B, O.
 Produce 4 genotypes:
 A, AB, B, O.
 O is _____________; individual needs to be homozygous for type.
 A and B are __________________; both can be expressed at the same time.
d)
Gender determination
 Mother has only _____ chromosomes; all eggs have an X chromosome.
 Father determines the gender of the baby; ________ chance for either
gender.
e) Sex linked traits
 Traits that are coded by genes located on ______ chromosomes (X or Y).
 Traits that are controlled by genes on the other 22 chromosomes are
___________.
 Use a Punnett square with sex chromosomes and the gene (___________________).
 Color blindness is an X linked trait; males need only 1 recessive allele to be colorblind,
women need 2.
2.3- DNA
 Deoxyribose Nucleic Acid- DNA
 Is a _____________shape (2 strands twisted); looks like a spiral staircase.
 Composed of ___________ = phosphate, sugar (deoxyribose), 1 Nitrogen base.
a) Structure
 DNA most often described as a double helix
• Closely resembles a twisted ladder
 Sugar and phosphate molecules form “______________” of ladder
 N bases form rungs
• N bases from one spine of ladder are connected with N bases from other by means of
_______________.
Nitrogen Bases
 There are 4 Nitrogen bases:
 Adenine (A)
 Guanine (G)
 Thymine (T)
 Cytosine (C)
 When 2 Nitrogen bases join (using a Hydrogen bond) they form a ____________.
 Only certain bases bond, due to chemical structures:
 ___________; ______________
b) Base pair bonding
 DNA
molecule has
1 base strand
and 1


_________________ base strand.
2 strands form the ladder, with the bonded pairs becoming the ‘rungs’.
What is the complementary strand to:
 ATTGCCGATGC _________________________
c) DNA Structure Determination
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•
Franklin collected x-ray diffraction data (early 1950s) that indicated 2 periodicities for DNA: 3.4
Å and 34 Å.
• Watson and Crick proposed a 3-D model accounting for the data.
• Proportion of nitrogen bases varies from species to species
• # adenine molecules = # thymine
• # guanine molecules = # cytosine
• N bases were arranged in___________
• Watson and Crick developed a 3 - D model of DNA molecule
d) Histones
 DNA from 1 cell is 2 meters long; it is coiled and wrapped around ______________
__________called histones.
 Used to reduce the needed space in nucleus.
e) Replication of DNA
 __________ is only molecule known that is capable of duplicating itself (replication)
• Helps explain how 1 cell can divide into 2 identical cells
 During replication, weak H bonds are broken
• 2 edges of the ladder seem to “__________"
▪ Parent strands are conserved.
• Each parent strand acts as a template to which ________________________ in cell can
attach
• Nucleotides attach themselves at their __________: adenine (A) with thymine (T), and cytosine
(C) with guanine (G).
• Enzymes,_____________, fuse free nucleotides together in complementary chain of DNA
 Free-floating nucleotides in cells are derived from the food one eats.
 ____ new strands of DNA are formed into the double helix.
f) The genetic code
 With only 4 bases, billions of genes can be coded.
 Proteins are made from specific _______ __________________ called genes.
 A protein is a chain of amino acids (1 of 20 building blocks of proteins); each amino acid is coded
by ____ bases together = DNA triplet code.
 64 possible codes but only ____ are used for amino acids in the human body.

g) Making Proteins
 DNA can’t leave nucleus (too large) so messenger RNA
(________) come and carry it to the ribosome.
 RNA does not have T but instead has ____________
 The ________( 3 bases) codes for an amino acid; these are joined
together in the ribosome.
Start and Stop codons
 mRNA takes DNA to __________ and tells them what protein to
make.
 Always code from the 5’ end to the 3’ end.
 To start or stop, a specific codon is used:
 Start = Initiator codon (_____).
 Stop = _______ codon (TAA, TAG, TGA).
h) Protein versatility
 Proteins are variable because they are made using specific amino
acids; some can even ______________and reverse when finished.
The body creates a protein for every need:
 Enzymes (polymerase).
 Structural ( body cells).
 _________________________
 Storage (Hemoglobin).
2.4- Mutations and Genetic Diseases
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 Mutation = ______________ in the sequence of bases in the DNA.
 Most occur naturally or due to radiation exposure.
 Each change is carried to next generation and _________________________.
 Mutations increase variability and lead to _________________ (beneficial and harmful).
a) Mechanism of Mutation
 Mutagenic agents can cause mutations:
 ________________________________.
 Dangerous for pregnant women in 1st trimester.
 Carcinogens are mutagens that are known to cause _____________ (uncontrolled cell growth): Xrays, cigarette smoke, pesticides…
 Mutations usually occur in chromosomal regions where they do not affect the protein; body can
______________ some mutations.
 Some mutations cause gene to stop working or alter function.
Beneficial mutations
 Mutations can allow for adaptation to the environment; _______________________, camouflage
coloring, etc.
 Allows for more chances to breed = more offspring with adaptation.
 Genetic inheritance is the key to ________ _____________________.
b) Types of mutations
 There are 2 types of mutations:
 ________________ (substitution of 1 base for another).
 ____________ mutations (deleting/adding a base during replication).
c) Passing on Mutations
 If a mutation is in an sex cell (sperm or egg); the mutation is passed to ___________.
 These diseases are genetic; the mutation is present in every cell of the offspring.
 In most cases a parent is a carrier and the mutated gene is ______________ to the healthy gene of
the other parent.
 ___ chance of having disease, ½ of carrier and ¼ healthy.
d) Genetic Diseases
 Each disease occurs because of a mutation on ___ of the chromosomes in the parent.
 Can be caused by recessive or dominant genes.
 4 common diseases are:
 Cystic Fibrosis (CF)
 _____________________
 Huntington disease
 ____________________
 Cystic Fibrosis: chromosome __, autosomal recessive, 1:2500 affected in Canada.
 Huntington’s: chromosome ___, autosomal dominant, 1:10 000 affected in Canada.
 Hemophilia: X chromosome, sex-linked recessive, 1:10 000 (higher % ___________).
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
Sickle cell anemia: chromosome 11, autosomal recessive, higher ______________ individuals
(link to malaria).
e) Pedigree Charts
 A genetic family tree; used to predict the _________________ of the individual.
 Used to trace genetic diseases.
 Uses specific symbols:
 Female = ____________
 Male = square
 Line between male and female = have children.
 Shaded = _________________
 Partly shaded = carrier for disease.
 Roman numerals = new generation.
g) Super bugs!
 Antibiotic resistant bacteria have adapted and mutated so they are ________________________.
 Every time the bacteria is exposed to an antibiotic, more become resistant- pass on to the new
bacteria.
 Bacteria reproduce asexually but can exchange material via _________________________.
 Transformation: Bacteria incorporate ______ ____________ into self.
 Plasmid: self-replicating ____________ piece of DNA that is transferred between bacteria.
 Plasmid may have the bacterial resistance gene and ______________ to all other bacteria.
 Promotes resistance in all strains of bacteria.
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2.5- Genetic Technologies
 Used to identify, treat and prevent hereditary disease; develop medicine, solve crimes and identify
individuals.
 ______________ issues arise with this new technology.
a) DNA fingerprinting
 In ________, DNA matching was used to identify a rapist-murderer in England
 In the same year, a rapist in Florida, was convicted on the basis of genetic evidence
 DNA fingerprinting test was developed by ______ ________________________.
• Particular segments of DNA are unique arrangements of nitrogen bases
• Only _______________________share same N base arrangements in these sections
• DNA segment is taken from semen found in rape victim. Compared with DNA segment taken
from a blood sample of suspect
• DNA samples are transferred to a _______________. DNA are tagged with a radioactive probe
that identifies unique segments of DNA chain
• Nylon sheet is then placed against an X-ray film
• Black bands appear where probes have attached to segments used to establish identity
• A ____________ is then made from film and used to compare samples
b) Transgenics
 Genes from 1 species are transferred and spliced into the________ of another species.
 Results in a genetically modified organism (_____).
 Used to create food, medicine or materials that will improve results.
 Crops with naturally producing pesticides.
 Bacteria that can produce insulin.
 Pig organs that are closely related to humans.
c) Gene Therapy
 Using genes to treat or _______ a disease.
 Using an _______________ to deliver needed gene to individual’s cells.
 Uses enzymes to cut healthy DNA into pieces---isolate needed ________-- insert into a plasmid--transfer to bacteria.
 ________________________= DNA with genes from 2 or more organisms.
 Used to treat Cystic Fibrosis and Diabetes.
 Cured the “bubble baby” by injecting bone marrow cells with an altered virus that produced
____________ _____________.
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