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NOTES : Chapter 6.1 – Chromosomes and Meiosis
KEY CONCEPT
Gametes have ______________ of chromosomes that body cells have.
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Body cells are also called __________ cells.
_______ cells develop into gametes.
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Germ cells are located in the __________ and ___________.
Gametes are sex cells: __________ and ______________.
Gametes have ________ that can be passed to offspring.
Your body cells have _____ pairs of chromosomes.
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____________ pairs of chromosomes have the same structure.
For each _______________ pair, one chromosome comes from each
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Chromosome pairs 1-22 are ________________.
___________________, ___ and ____, determine gender in mammals.
Fertilization between egg and sperm occurs in ________________________.
______________ (____) cells have _____ copies of every chromosome.
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________ cells are diploid.
_________ the chromosomes come from each _____________.
____________(___) cells have ______ copy of every chromosome.
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_____________ are haploid.
Gametes have ________________ and ____________________.
• Chromosome _____________ must be maintained in animals.
• Many plants have more than ________________ of each chromosome.
• _____________ and _____________ are types of nuclear division that
make different types of cells.
• Mitosis makes more _______________ cells.
• Meiosis makes ___________ cells from ____________ cells.
- Meiosis occurs in _______________.
- Meiosis produces __________________.
Chpater 6.2 – Process of Meiosis
KEY CONCEPT
During meiosis, diploid cells undergo______ cell divisions that result in ___________ cells.
Cells go through two rounds of division in meiosis.
Meiosis ______________________ number and creates _____________ diversity.
Meiosis I and meiosis II each have _________________, similar to those in _________________.
– Pairs of ________________ chromosomes __________________ in meiosis I.
– Homologous chromosomes are similar but _______________________.
–_________________chromatids ________________ in meiosis II.
– Sister chromatids are ________________ of the _____________ chromosome.
• Meiosis I occurs after _______ has been ________________.
• Meiosis I divides homologous chromosomes in four phases.
• Meiosis II divides ____________ chromosomes in four phases.
•__________ is _________ replicated between meiosis I and meiosis II.
•Meiosis differs from mitosis in significant ways.
- Meiosis has _______________________________ while mitosis has __________.
- In mitosis, homologous chromosomes __________________________.
- Meiosis results in ________________ cells; mitosis results in ________________ cells.
•Gametogenesis is the production of _________________.
•Gametogenesis differs between females and males.
•_____________ become motile.
•Sperm primarily contribute ____________ to an embryo.
•Eggs contribute _____________, __________________, and ________________ to an embryo.
•During meiosis, the egg gets most of the contents; the other cells form ___________________.
Note 6.3 - Mendel and Heredity
KEY CONCEPT
Mendel’s research showed that traits are inherited as discrete units.
• _________________ are distinguishing characteristics that are _____________________.
•__________________ is the study of biological inheritance patterns and variation.
• _______________________ showed that traits are inherited as discrete units.
• Many in Mendel’s day thought traits were _________________.
•Mendel made three key decisions in his experiments.
– use of _________________ plants
– control over ____________________
– observation of seven “either-or” traits
– Mendel used ______________ to fertilize selected pea plants.
– _____ generation crossed to produce ___________ generation
– interrupted the self-pollination process by removing ________________________
–Mendel allowed the resulting plants to _____________________.
– Among the F generation, all plants had _____________ flowers
– F plants are all _________________ ( ________________________)
– Among the ___ generation, some plants had __________ flowers and some had _________
–Mendel drew three important conclusions.
– Traits are inherited as discrete units.
– Organisms inherit _________________ of each gene, one from each __________.
– The two copies ______________ ( _______________) during gamete formation.
– The last two conclusions are called the ______________________________.
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Notes 6.4 - Traits, Genes, Alleles
KEY CONCEPT
Genes encode ____________________ that produce a diverse range of traits.
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The same gene can have many versions.
- A __________ is a piece of DNA that directs a cell to make a certain ______________.
- Each gene has a _______________, a specific position on a pair of homologous
chromosomes.
•An _________________ is any _________________ form of a gene occurring at a specific ___________ on
a chromosome.
• Each parent donates one ____________
for every _________.
• ____________________ describes two alleles
that are the __________ at a specific locus.
• _____________________describes two alleles
that are______________ at a specific locus.
•All of an organism’s genetic material is called the _____________.
•A _________________ refers to the makeup of a specific set of genes.
•A ________________________ is the physical expression of a trait.
 Alleles can be represented using _______________.
 A _________________ allele is expressed as a phenotype when at least one allele is dominant.
 A__________________ allele is expressed as a phenotype only when two copies are present.
 Dominant alleles are represented by ____________ letters; recessive alleles by ________________ letters.
•Both homozygous dominant and heterozygous genotypes yield a dominant phenotype.
•Most traits occur in a range and do not follow simple dominant-recessive patterns.
Notes 6.5 - Traits and Probability
KEY CONCEPT
The inheritance of traits follows the rules of probability.
• The _______________________ is a grid system for predicting all possible _________________ resulting
from a cross.
– The axes represent the possible gametes of each parent.
– The boxes show the possible genotypes of the offspring.
The Punnett square yields the ____________ of possible _______________ and _______________.
A ____________________ cross involves one trait.
A __________________ is a cross between an organism with an unknown genotype and an organism with
the ______________________ phenotype.
A ___________________ cross involves two traits.
Mendel’s dihybrid crosses with ________________________ plants yielded a _______________
phenotypic ratio.
•Mendel’s dihybrid crosses led to his second law, the law of __________________________.
•The law of _____________________________________ states that allele pairs separate
______________________ of each other during meiosis.
• _____________________________ is the likelihood that something will happen.
•_____________________________ predicts an average number of _____________________, not an exact
number of occurrences.
Notes 6.6 - Meiosis and Genetic Variation
KEY CONCEPT
_________________________________ and ___________________________ during meiosis result in
genetic diversity.
• ______________________reproduction creates unique combination of genes.
–independent assortment of chromosomes in meiosis
–random fertilization of gametes
• Unique _________________________ may give a reproductive advantage to some organisms.
• _____________________________ during meiosis increases genetic diversity.
•Crossing over is the exchange of ________________________________ between
_______________________ chromosomes.
– occurs during ______________________ of meiosis I
– results in _______________________________ of genes
– The farther apart two genes are located on a chromosome, the more likely they are to be separated
by crossing over.
–Genes located close together on a chromosome tend to be ___________________________, which
is called ______________________________.
•________________________________ allows the distance between two genes to be calculated.
Chapter 7 Notes (7.1 - Chromosomes an Phenotypes)
KEY CONCEPT
The chromosomes on which genes are located can affect the expression of traits.
Two copies of each _____________________ gene affect phenotype.
• Mendel’s rules of inheritance apply to autosomal genetic disorders.
• A heterozygote for a recessive disorder is a ________________(Cc).
• Disorders caused by dominant alleles are uncommon. (Achondroplasia)
(do
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•Genes on sex chromosomes are called ____________________ genes.
–Y chromosome genes in mammals are responsible for __________
characteristics.
– X chromosome genes in mammals affect __________ traits. So most sexlinked traits are found on the ______-chromosome.
•Male mammals have an __________ genotype.
• All of a male’s __________________________ (those on X-chromosome) are expressed.
• Males have no ___________________ of sex-linked genes, so the X-chromosome traits will be
displayed. X b Y = only “b”
Example: __________________________
•Females have ________ genes, while males have only ________
•Female mammals have an __________ genotype.
•Expression of sex-linked genes is similar to _________________ genes in females. X
•X chromosome ______________________ randomly “turns off” one X chromosome.
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X b - Bb
Chapter 7 Notes (7.2 - Complex Patterns of Inheritance)
Phenotype can depend on interactions of alleles.
• In ________________________________, neither allele is completely dominant nor completely
recessive.
– Heterozygous phenotype ________ is ___________________ between the two homozygous phenotypes
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– Homozygous parental phenotypes not seen in ______________________
_________________________ alleles will both be completely expressed.
–_____________________________ alleles are neither dominant nor recessive.
–The ABO blood types result from _______________________ alleles.
–Many genes have more than _______ alleles.
•_________________________________ are produced by two or more genes.
The _____________________ interacts with genotype.
• Phenotype is a combination of _________________ and ______________________.
• The sex of sea turtles depends on both genes and the environment
Chapter 7 Notes (7.3 - Gene Linkage and Mapping)
KEY CONCEPT
Genes can be ___________________ to specific _______________________ on chromosomes.
•The _________________________ two genes are, the more likely they will be inherited together.
• _______________________________ frequencies are related to ___________________ between genes.
• ___________________________ show the relative locations of genes.
Chapter 7 Notes (7.4 - Human Genetics and Pedigrees)
KEY CONCEPT
A combination of methods is used to study human genetics.
Females can _________________ sex-linked genetic disorders, but not _________________ them.
•_____________________________ express all of their sex linked genes.
• Expression of the disorder depends on which parent ____________ the allele and the __________ of the
child.
A ______________________________ is a chart for tracing genes in a family.
• ____________________________ are used to infer genotypes on a pedigree.
•If the phenotype is more common in males, the gene is likely ____________________________.
A ________________is a picture taken during __________________________of all chromosomes in a cell.
• ____________________ can show changes in chromosomes.
• ___________________ of part of a chromosome or ____________ of a chromosome
• __________________________ in chromosomes
•____________________________ or ___________________________ of part of a chromosome