Download Under TOUR OF BASIC GENETICS, click

Basic Genetics: Extra Credit
Mr. Distasio
Name _______________________________________ per. _______
http://learn.genetics.utah.edu/content/basics/
Under TOUR OF BASIC GENETICS, click
1) What are Traits?
Play the video clip.
What are the two factors that control our traits?
___________________________________
___________________________________
Scroll down to fill in the following information….
Identical twins: same DNA, different environment
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
Identical twins have exactly the _______________ DNA, but they are not exactly alike. Each
twin has his or her own personality, talents, likes, and dislikes. There are even diseases that
appear in one twin but not the other, including arthritis, diabetes, autism, schizophrenia, cancer,
and many others. The differences between identical twins don't come from DNA—they all come
from __________________ factors.
Scientists often study twins to understand how ______________ and the
__________________________ work together to affect traits. They compare traits in
_____________________ twins, who have identical DNA, and
_____________________________ twins, who share half their DNA, just like any siblings. If a
characteristic appears more frequently in identical twin pairs than in fraternal twin pairs, then it
has an ______________________ component.
Click the Next Stop: What are DNA and Genes? link under the video
2) What are DNA and Genes?
Play the video clip

What letters are used to represent the four bases found in DNA? _____, _____, _____ & _____

DNA is made of _____ (#) complimentary strands.

Describe the base pairing rules in a DNA strand:

Define gene: __________________________________________________________________
A binds with _____, C binds with _____.
__________________________________________________________________

Define genome:
____________________________________________________________
____________________________________________________________

“Every person’s _____________________ has the same __________ arranged in the ________
order, but small differences in the _______________________ of the __________ in our genes
make each person _________________”
Scroll down to fill in the following information….
DNA is all the same chemical

The stringy stuff in the test tube is DNA. But you can't tell which one of these organisms it came
from just by looking at it. That's because ___________________________________________
____________________________________________________________________________

___________________________________ have DNA. And whether it comes from you, a pea
plant, or your pet rat, it's all the same molecule. It's the order of the________________ in the
code that makes each organism different.
The human genome

The order of building blocks in a strand of DNA makes up a "sequence." We can read a DNA
sequence like letters in a book. In fact, we know the sequence of the entire human genome—all
3 ___________________ letters. That's enough information to fill roughly 1,000 200-page
books!

Contained within the 3 billion letters of the human genome are about ___________________
genes. Most of our known genes code for proteins, but some code for RNA molecules.
Your DNA makes you unique

All humans have the __________ genes arranged in the ____________ order. And more than
_______% of our DNA sequence is the ____________. But the few differences between us (all
1.4 million of them!) are enough to make each one of us unique. On average, a human gene will
have _______ bases that differ from person to person. These differences can change the
___________ and ______________ of a protein, or they can change _____ _______ protein is
made, ________ it's made, or ________ it's made.
Scroll back up and click the Basic Genetics tab and go to “What are Proteins”
3) What are Proteins?
Play the video clip

The instructions for making proteins are found in segments of DNA called _________________

Proteins are made of long chains of building blocks called ________________
______________. There are _________(#) amino acids.

The ____________ of the protein is important in determining it’s function.
Proteins are the workhorses of our bodies

Proteins make up about _____ % of the dry weight of our bodies. The protein
______________—which holds our skin, tendons, muscles, and bones together—makes up
about a quarter of the body's total protein.
All of our cells and even ___________________ are packed with protein molecules.
Proteins are versatile

A protein's three-dimensional _____________ is uniquely suited to its function. The ____
different _____________ ___________ building blocks can be arranged in different ways to
form a nearly infinite assortment of protein shapes.

Different arrangements of amino acids can make proteins that are extremely strong, as in
________ fibers, or flexible and elastic, as in the ___________ in our skin. And like pieces of a
jigsaw puzzle, proteins can ___________________ with other molecules. For example, each
type of ________________ in our blood has a unique arrangement of amino acids at its tips that
can attach to a specific _________________, marking it for destruction by the immune system.
Proteins work together

Proteins need to physically ___________________ with each other and with other molecules to
do their work. These interactions might activate an __________, turn on a _________, or
communicate a _____________ from one cell to another.

Interactions between proteins depend not just on their ______________ but also on their
______________ properties: positively and negatively _____________ amino acids are
attracted to each other; hydrophobic residues cluster together, away from water. These physical
properties allow proteins to interact in specific ways.

Multiple proteins can come together to build a molecular _____________________.
Proteins change shape

Cells are alive with motion, much of it driven by proteins. Many proteins are flexible and
dynamic. _______________ proteins, for example, bend and swing to literally walk across the
cell's cytoskeleton. And when the neurotransmitter _____________________ binds to its
receptor, the entire protein molecule shifts, causing a _________ to open up at its center.
Sodium ions to pass through the opening, starting a chain reaction that will fire a nerve signal
across the brain.
Proteins are recycled

Like us, plants and animals are made of proteins. When we eat them, we eat protein. Highprotein foods such as ___________, ___________, ___________, _______________,
__________, and _______________ give us both energy and building blocks to grow and
maintain a healthy body.

The proteins we eat are broken down into their individual __________ _________ building
blocks. We reuse these amino acids to build new __________________
Click the Back button and go to “What is Inheritance?”.
4) What is Inheritance?
Play the video clip

When living thing reproduce, they pass ______ to their offspring.

Through _________________ reproduction, some living things can reproduce without a partner.
Offspring made this way are _____________________ ____________________ to the parent.

Offspring from sexually reproducing organisms inherit _________________ _______________
of DNA from each parent.

Each of us has _____ copies of every gene, one from each _______________. Each child gets
a ___________________ combination of all their parents’ genes – this mixing results in
____________________ within a species.
Sources of variation

Genetic ____________________ is important because when conditions change (food becomes
scarce, environment changes), some individuals in a population will be more likely to have
variations that will allow them to __________________. Those who reproduce pass their genes
to the next generation. Variation helps species survive, and it's the reason _____________
_____________ _________ ___________.

In asexual reproduction, variation comes mainly from _______________. Mutation is a natural
process that introduces permanent ____________ in a _________ sequence. However,
microbes also acquire genetic variation through transformation, transduction, and conjugation
(gene transfer). These mechanisms often come into play when conditions are harsh.

In sexual reproduction, variation comes from both _______________ and
_____________________. Mutation creates the different versions (or alleles) of the same gene.
Parental alleles are then shuffled—or recombined—during ____________. Because of
recombination, __________________reproduction produces more variation than
_______________ does.
Patterns of inheritance

Most commonly, traits are influenced by ________________ ____________ and the
___________________. So for most traits, patterns of inheritance are complex and
unpredictable. For instance, when a sexually reproducing organism inherits a defective or
"broken" allele that codes for a non-functional protein, the second copy can often make up for
the loss. This type of interplay between alleles, especially when traits are influenced by multiple
genes, makes predicting inheritance ____________, if not impossible.

A small number of traits are influenced primarily by a ____________ gene. Traits influenced
mainly by one gene usually have predictable patterns of inheritance. However, most of the time
even supposed "single-gene" traits are influenced by multiple genes, as in the case of eye color.
And often times, a single gene can influence ____________ traits. For example, some genes
involved in eye color also influence ________ and _________ color.
Sex chromosomes

It's not quite accurate to say that everyone inherits two copies of every gene. In most mammals,
the _____ and_____ sex chromosomes determine whether an individual is male or female.
Females have ___ X chromosomes, and therefore two copies of every gene. Males, however,
have one X and one _____ chromosome. For genes that appear only on the X chromosome or
only on the Y (some do appear on both), males inherit just one copy.

Other living things have sex chromosomes too. Birds and reptiles have Z and W sex
chromosomes. Unlike with X and Y, males have two Z chromosomes, and females have one Z
and one W. Some insects and a few mammals have only an X chromosome. Females have two
copies and males have one. However, sex is _____ _____________determined by
chromosomes. With alligators, crocodiles, and most turtles, it's egg incubation
_______________. And some fish can change gender in response to cues from the
environment. Sex determination happens in many different ways.
Click “Next Stop: What is Mutation?
4) What is Mutation?
Play the video clip
 True or False: Mutations are extremely common
 True or False: Mutations are always bad.
 Because of mutations, each one of us has about _____ new variations that were not present in
our parents.
 Whether or not a mutation has an effect or not largely depends on the _______________ of the
mutation.
Mutation Generates New Alleles

The whole human family is _______ species with the __________ genes. Mutation creates
slightly different versions of the same genes, called _______________. These small differences
in DNA sequence make every individual unique. They account for the _________________ we
see in human hair color, skin color, height, shape, behavior, and susceptibility to disease.
Individuals in other species vary too, in both physical appearance and behavior.

Genetic variation is useful because it helps populations __________ over time. Variations that
help an organism _______________ and __________________ are passed on to the next
generation. Variations that hinder survival and reproduction are ____________________ from
the population. This process of _____________ _________________ can lead to significant
changes in the appearance, behavior, or physiology of individuals in a population, in just a few
generations.

Once new alleles arise, _____________ and __________________ reproduction combine
different alleles in new ways to _________________ genetic __________________.
Mutation vs. variation

It's useful to think of mutation as a ______________________________________________.
We often refer to a mutation as a thing—the genetic variation itself. This approach can be useful
when it comes to a gene associated with a disease: the disease allele carries a mutation,
__________________________________________________. However, this approach gives
mutation a bad name.

It’s important to remember that losing the function of a gene ____________ always affect health.
For example, most mammals have hundreds of genes that code for olfactory receptors, proteins
that help us smell. Losing one of these genes probably doesn’t make all that much difference.

In contrast to variations that cause disease, there are many more examples of variations that are
neither good nor bad, but just ____________—like blood types and eye color. Just like with
disease alleles, the process of mutation creates these more _______________ variations. But
with neutral variations, it can be impossible to tell which allele is the "normal" one that existed
first and which is the "mutant"—and the distinction is often meaningless.
Proteins and switches

Mutation creates variations in _____________________ portions of genes that can affect the
________________ itself. But even more often, it creates variations in the "_______________"
that control _______ and __________ a protein is active and _____ ______ protein is made.

____________________is an enzyme that helps infants break down lactose, a sugar in milk.
Normally the gene that codes for lactase is active in babies and then turned off at about age
_________. When people who don't make lactase consume milk, they experience gas, nausea,
and discomfort. But some people have a variation in a genetic switch that keeps the lactase gene
________________. This variation is called "lactase persistence," and people who have it can
keep milk in their diets even as adults.
Other drivers of mutation: Environmental agents

____________________, ____________________, byproducts of cellular metabolism, free
______________, __________________ rays from the sun—these agents damage thousands
of nucleotides in each of our cells every day. They affect the _________________ themselves:
converting one base to another, knocking a base off its backbone, or even causing a break in the
DNA strand.
DNA Repair

Most of the time, mutation is _______________. DNA repair machines are constantly at work in
our cells, ________________ mismatched nucleotides and splicing broken DNA strands back
together. Yet some DNA changes remain. If a cell accumulates ___________ changes—if its
DNA is so damaged that repair machinery cannot fix it—it either stops dividing or it selfdestructs. If any of these processes go wrong, the cell could become ___________________.

When we put on sun screen, we are protecting ourselves against mutation in
____________________ cells—the cells that make up the body and are not involved in
reproduction. Only when DNA changes are carried in _____ and __________ cells are they
passed to the next generation. Believe it or not, a certain amount of sloppiness is built into the
system. Without mutation there would be no ____________, and without variation there would
be no _____________________.
Return to the Tour index
How do Scientists Read Chromosomes?
To "read" a set of chromosomes, scientists use three key features to identify their similarities and
differences:
1. _______________. This is the easiest way to tell chromosomes apart.
2. _______________ ______________. The size and location of Giemsa bands make each
chromosome unique.
3. _______________ ______________. Centromeres appear as a constriction. They have a role
in the separation of chromosomes into daughter cells during cell division (mitosis and meiosis).
Using these key features, scientists can identify all 46 chromosomes - one set of 23 from each parent
What are centromeres for?

___________________are required for chromosome separation during cell division. The
centromeres are attachment points for ______________________, which are protein fibers that
pull duplicate chromosomes toward opposite ends of the cell before it divides. This separation
ensures that each ___________________ cell will have a _____ ______ of chromosomes.
Each chromosome has only ________ centromere.
During cell division, _________________________attach to centromeres and pull the chromosomes to
opposite ends of the cell.
Centromere Positions

The position of the centromere relative to the ends helps scientists tell chromosomes apart.
Centromere position can be described three ways: metacentric, submetacentric or acrocentric.

In _________________________ chromosomes, the centromere lies near the center of the
chromosome.

_________________________ chromosomes have a centromere that is off-center, so that one
chromosome arm is longer than the other. The short arm is designated "p" (for petite), and the
long arm is designated "q" (because it follows the letter "p").

In _______________________ chromosomes, the centromere is very near one end.
Scroll back up and click Basic Genetics. Choose “Make a Karyotype”
Make a Karyotype

A ____________________ is an organized profile of a person's chromosomes. Two
chromosomes specify gender : _______ for female and ______for male. The rest are arranged
in pairs, numbered 1 through 22, from __________ to ___________. This arrangement helps
scientists quickly identify chromosomal alterations that may result in a genetic disorder.

Complete the interactive activity “Matching Up Chromosomes in a Karyotype”
Scroll back up and click Basic Genetics. Choose “Using Karyotypes to Diagnose Genetic Disorders””
Using Karyotypes to Diagnose Genetic Disorders

A regular human cell has _____ chromosomes: 44 __________________, which come in pairs,
and 2 ________ chromosomes, which specify gender (_____ for female and _____ for male).

The pairs of autosomes are called "__________________ chromosomes." One of each pair
came from _______ and the other came from _________. Homologous chromosomes have all
of the same ____________ arranged in the same __________, but with slight differences in the
______ _________________ of the genes.
What happens when a person has something different, such as too many or too few chromosomes,
missing pieces of chromosomes, or mixed up pieces of chromosomes?
Fertilization


Before we look at how the process can go wrong, let's take a look at how cells normally
get 46 chromosomes.
Egg and sperm cells have just ______ chromosomes each. That's _______ as many
chromosomes as regular cells. Through the process of ____________________, egg
and sperm join to make a cell with 46 chromosomes, called a ______________.
Mitosis

Before the zygote divides to make two cells, it _________ each chromosome. These copies,
called sister ______________________, are ___________________. When the zygote divides,
each cell gets one identical copy of each chromosome. The cells continue dividing this way to
make a person. This type of cell division is called __________________.
Meiosis

When egg and sperm form, they go through a special type of cell division called ____________.
One purpose of meiosis is to reduce the number of chromosomes by ___________. The other
is to create genetic _____________________.

Meiosis begins like mitosis: the cell copies each chromosome. But unlike in mitosis,
_______________ chromosome pairs line up and exchange pieces—a process called
_____________________. Remember, homologous chromosomes have the same genes but
with slight differences. Recombination increases genetic _____________ by putting pieces of
chromosomes that came from _____ together with pieces of chromosomes that came from
_____.

Next, the newly recombined homologous chromosomes are divided into ______ daughter cells.
Then the sister _____________ are pulled apart into a total of _______ cells. Each of these
cells has ______ copy each of 23 chromosomes, all with a __________________
__________________ of mom's and dad's genes.
Too Many or Too Few Chromosomes

Sometimes chromosomes are incorrectly distributed into the egg or sperm cells during meiosis.
When this happens, one cell may get ______ copies of a chromosome, while another cell gets
______. Incorrect distribution of chromosomes is called _______________________.

If a sperm or egg cell with too many or too few chromosomes participates in fertilization, it will
produce a ________________ with too many or too few chromosomes. A zygote with 3 copies
of a chromosome is said to have _________________ . A zygote that is missing a
chromosome is said to have ______________________.

Most of the time, __________________________ (non-sex chromosome) trisomy and
monosomy are _________________ because the zygote ends up with too much or too little
genetic information. But sometimes, babies are born with extra or missing autosomes—most
commonly one of the smaller chromosomes that have fewer genes. Usually these babies have a
____________ ______________, which scientists can diagnose by looking for extra or missing
chromosomes in a ____________________.

When monosomy or trisomy involves _______ chromosomes, individuals usually survive and
many are quite healthy.
Genetic disorders resulting from too many or too few chromosomes include:

_______________________________ (XXY)

_______________________________ (X)

_______________________________ (Trisomy 21)
Missing Pieces

Sometimes pieces of chromosomes are lost or rearranged during _______________. This
happens during the ________________________step, when maternal and paternal
chromosomes swap pieces.

When genetic material is missing, a chromosome is said to have a ________________.
Deletions of the tips of chromosomes are called ____________ deletions. Internal deletions,
where a chromosome has broken, lost material, and rejoined, are called _______________
deletions.

Chromosomes with deletions large enough to be visible on a karyotype are ____________many
genes. In humans, such large deletions are less common than smaller deletions, which often
cannot be seen on a karyotype. As with too many or too few chromosomes, deletions can cause
genetic disorders. The symptoms of deletion disorders vary, depending on which genes are
missing.
Click “Play” on the Image File
1) What is a terminal deletion?
_________________________________________________
_________________________________________________
2) What is an interstitial deletion? _________________________________________________
_________________________________________________
Genetic disorders resulting from chromosome deletions include:

_____________________________ (Chromosome 5)

_____________________________ (Chromosome 7)
Translocations

A __________________________ is a chromosome rearrangement in which part of a
chromosome ______________ _______ and then __________ to a ______________________________chromosome. Types of translocations include reciprocal and
Robertsonian.

A _________________ translocation is a swap between two chromosomes. In a balanced
translocation, the individual has all of their genes, and they are typically healthy. A translocation
where genes are also duplicated or deleted is called an unbalanced translocation. Individuals
with extra or missing genetic material usually have a genetic disorder.

A ________________________________ translocation occurs when the long arms of two
acrocentric chromosomes fuse at a centromere. The two short arms are lost, leaving a total of
45 chromosomes. But because the short arms carry very little genetic information, individuals
with Robertsonian translocations are usually healthy.
Click “Play” on the Image File for a visual of two types of translocations