Title

Gene Definition

A. Definition -- a gene (A _ L _ _ E) is a segment of a

C _ _ O _ O _ _ M _

which often codes in this
_ _ _ molecule

    for the production of a single
    P _ O _ E _ N      a.k.a.   a
    (P _ _ Y _ _ P _ I _ E).

The subunits of proteins are
known as _ M _ N _ A _ _ D _

   and they are connected together
   to form complex proteins at
   cytoplasmic organelles known as
   R _ _ O _ O _ _ S.

    Some of these proteins for which the original gene
    coded form cellular and physical body structures that
    we can actually see such as H _ _ _

    (Unbelievable, that is a person standing there.   I also
    thought it was a weird shocking pink ice-cream cone,
    but I too was wrong.)

and proteins such as N _ _ L _,

   while other proteins known as
   _ N _ Y _ _ S (Gee! this diagram
   looks very familiar) function to
   regulate the R _ _ E of
   chemical reactions

Definition Revisited -- I used so many pictures in this gene definition that it was spread
out perhaps too much. Here's the original definition in one place. This may help you.

A gene (A _ L _ _ E) is a segment of a C _ _ O _ O _ _ M _ which often codes in its
_ _ _ molecule for the production of a single P _ O _ E _ N (P _ _ Y _ _ P _ I _ E).
The subunits of proteins are known as _ M _ N _ A _ _ D _ and are connected
together to form complex proteins at organelles known as R _ _ O _ O _ _ S. Some
of these proteins form cellular and physical body structures that we can see such as
H _ _ _ and N _ _ L _, while others known as _ N _ Y _ _ S function to regulate
the R _ _ E of chemical reactions

Click here to see the answers to this section!

Many Genes Sometimes Control One Trait

B. (First attempt) GENERAL RULE --- (See #1 below and to the right!)

                 1.    Since you have two biological parents, both
            the two pictured fly C _ R _ _ O S _ _ E _
            (One above the map and one below it) and
            the G _ _ E _ on them occur in pairs. You
            know what a pair is -- _ _ _   of a kind in
            length, shape and gene markings.

A           (a) Here we see three different chromosomes
    with specific genes (Ex. G1, T1, A1 etc.)
    identified on the top chromosome.

                These chromosomes should each be shown
    in P _ _ R _, but I can't control what images I
    find in web searches.

(b) Each pair of genes usually controls a _ _ N _ _ _ trait, as suggested by the two
examples which follow. But there are also exceptions to this rule which follow.

                       (c) This is Tongue R O _ _ _ N G,  a
                 single trait controlled by a single
                 _ _ _ _ of genes.

        (d) Here's another trait controlled by only a
        S _ _ _ _ E   pair of genes. When your
        hands are lined up this way, either your
        little fingers are straight or they are B _ _ T.

(e) This pattern of one pair of genes controlling one trait is very common in human biology,
but that does not mean it is the only pattern of inheritance.

2. Sometimes M _ _ _ T _ _ N one pair of genes control one inherited trait. Here are
three common human traits that are each controlled by M _ _ _ I P _ E pairs of genes.

                                                                                               (a)    Example 1 -- four pairs of genes
        regulate human S _ _ _
        pigmentation.

        Here's a world map showing
        regions of this planet and the
        degree of skin pigmentation
        shown by a typical resident of
        that region.

        On this world map, it seems
         that E _ U _ T _ R _ A _
         regions have people with the
         darkest pigmentation.

(b)                     (b) Example 2 -- At least two pairs of genes also
                        regulate human _ Y _   pigmentation.
                        (Some books say two pairs and some say three!)

                              By far the least amount of deposited pigments
                        (look at the density of spots in the iris of the eye)
                        occurs in people with which of the eye colors
                        on the left? Your answer should be true _____ .

        (c)   Example 3 -- Many
        pairs of genes control
        human H _ _ _
        pigmentation. This
        is a shaft from a
        person with light
        colored hair.

Example 3 -- At least three pairs of genes regulate human H _ I _ _ T

              Some people have tall genes from both sides of
        the family. Would you believe both of this man's
        parents were basketball players? It's true. And
        Y _ _ is about 7'6" as a result. Sure looks like
         he got a lot of genes for T _ _ _ N _ _ S.

            And some people despite having
      normal parents end up with genes
      for S _ O _ T _ E S _ or at least
      genes for some hormone deficiency
      resulting in short stature. .

            This is Nelson DeLaRosa from
      the Dominican Republic. He's the
      World's shortest person according
       to Guiness.

            Nelson gained fame during the 2004 baseball
      season when he visited another famous
      Dominican in Boston. A lot of people did not
      like that P _ _ _ O lifted Nelson into the
      air.   Who knows?? Maybe that's part of the
      reason the Red Sox did not resign this star
      pitcher who then jumped to the Mets for the
      2005 season.

Click here for the answers to this section.

B. (Second attempt) GENERAL RULE --- A single pair of genes usually controls a
_ _ N _ _ _ trait, but here's another exceptions to this "rule."

(2) Sometimes a S _ _ G _ _ pair of genes can influence more than one trait.

Example #1 follows: (Remember italics is optional for Bio R)

      (a) Example 1 -- In certain mice, the gene
    for yellow fur is dominant (symbol = __)
    to that for the recessive gene for gray
    fur (symbol = __). If two heterozygous
   yellow mice are bred, what is the
expected outcome (color ratio)
(____OTYPE) of their offspring in
   the following Punnett Square?

          :
                            Mom

Dad

To answer this, complete thus Punnett Square!

You would expect __ yellow mouse/mice : __ gray mouse/mice.

Surprise! The actual obtained data in L _ _ G _ numbers of matings is approximately 2 yellow: 1 gray. Other experiments showed that all the yellow offspring mice were heterozygous. This is not what we predicted in the Punnett Square.

From the Punnett Square, which genotype in real life is missing? Answer = __ __.
It turned out that the missing mice had never been born; the mother had miscarried
ALL of them. The dominant gene (allele) symbol Y controls __ (a number) trait(s)
in these mice as given in (1), (2) to follow..

            ((1)) The heterozygous condition (genes __ __) produces __________ fur
            ((2)) The homozygous condition, (genes __ __) is a L E _ _ A _   gene
                     (ask actors Mel & Danny if you don't know this word!)

Example #2 Follow: (Regular type -- All students resume work here!)

The trait for lack of skin pigmentation is known as A _ B _ _ I _ M. You probably are
more familiar with the other noun A _ B _ _ O which is an organism which lack such
pigmentation. This G _ _ E M _ _ A T _ O _ for lack of melanin occurs in many species, although it is rare in most of these species. Sometimes humans artificially select these
non-pigmented organisms for breeding to have an entire race of them. Here are some
examples of albinos in many species. You must name the species for each photo.

a) Cutie here is a lab _ _ _. Since s/he is an albino,
s/he blends in perfectly with a white background.

    b) This is a WHITE TAILED- _ _ _ _,
         but who can tell since we can't see
         the tail and the whole organism is
         now white.

   c)    And this is an albino _ _ N _ U _ N

          Notice that this guy seems isolated from
          the rest of the group. I wonder if
          prejudice exists in this species!

d) Puppy Power! Some dog breeds are
selected because they are all albinos.

And humans are not exempt either. Here's a collection of human albinos.

I can't get rover & its twin out of here!

Look for the two different similarities in many of the albinos pictured above.
Lack of pigmentation (hair, skin & eyes) is not the only trait affected by this albino gene
See if you can figure out one other similarity (trait) in some of those shown above.

(b) Example 2 -- In humans a person who is homozygous for the two genes for albinism
      (of course one from the M _ _ _ _ R and one from the F _ _ H _ R) lacks two separate
      distinct traits. Most of these people lack both the trait for adequate
      P _ _ _ E _ T _ _ I O _    and lack good E _ _ S I _ _ T.   As stated before, this is the
     results of   _ _ _   gene which controls _ _ _   different traits.

(3) A human cell contains many thousands of different genes in its chromosomes found in
its N _ C _ _ _ _.

Click here to see your answers.

C. Chemical components of genes.

(1) In most handsome organisms, the coded instructions for specifying the
characteristics of the organism are carried in

         _ _ _ molecules (pictured on the left),
    formed from subunits known as nucleotides.
    These nucleotides which have major
    portions in common also have subparts
    which differ.

         These four different subparts of a
    N _ _ _ E _ T _ _ E are kinds of
    Nitrogen B _ _ _ _.   CLUE
    One is Guanine represented by the letter __
    One is Cytosine represented by the letter __
    One is Adenine represented by the letter __
    One is Thymine represented by the letter __.


These four letters are the only parts of the DNA molecule which differ
and allow genes to differ between individuals and between species.

(2) The chemical and structural properties of DNA bases are the basis for
how the genetic information that makes up (underlies) heredity is both
encoded in ...

G _ _ _ S (as a string of molecular “_ _ _ _ _”)
and

    R E _ L _ _ A _ _ D (this means copied exactly as
    in a work of art) by means of a    T E _ P _ A T _
    (examples) (pattern of bases).

Here are the answers for you!

D. Changes in Genes

             Changes in genes are passed
    on to subsequent generations
    of C _ _ _ S (pictured)

by the process of M _ _ _ S I S.
(pictured on the left)

      (1) Any change of the DNA sequence is
        known as a M _ _ A _ _ O N.

Usually, a changed gene will be passed
on to every cell that develops from it.

Syndactyle (fused digits)

(2) People therefore think that all future generations of cells ...

   (pictured on the left) from this altered
   cell would have to be (different/ alike)
    _____________.

(3)   Surprise!   This is usually, but not always the interesting case.
                The many body cells in an individual can be very D _ _ _ E _ E _ T
                from one another, even though they are all descended from a
                S _ N _ _ E cell, created by the cellular process of M _ _ O S I S
                and thus have I _ _ N T _ _ A _ genetic instructions.

      This is because different parts of these _ _ _ instructions are used in
                different types of cells (more information), and are influenced by the
                cell’s environment and past history.

(a)

            A white blood cell will only use those
       genes which tell it how to function as a
        ___________ cell.

(b)

            A skin cell will only use those genes
      which tell it how to function as a
       _______ cell.

(c)

            A liver cell will only use those
        genes which tell it how to
        function as a ________ cell.

(d) You get the idea by now!

            As time goes by, cells start to
       D _ _ _ E _ E _ T _ _ _ E into
       different cell types such as
       blood cells, skin cells and
       liver cells.

Cell Differentiation

Click here for your answers.

E. Mutations

        Mutations occur as R _ _ _ O M
      (chance) events and are usually
      H _ _ _ F U L. Two heads are not
      always better than one you see.

      (Clue, if you have a model airplane that
      flies well and then randomly change a part of the design, are you more
      likely to help or to harm the functioning of the design?)

(1)

            Gene mutations in a cell can
      sometimes result in uncontrolled
      cell division which invades and takes
      over formerly healthy tissues. This is
      a group of diseases called C _ _ _ E _.

(2)

Exposure of cells to certain harmful E N _ _ _ O _ M _ _ _ A L
factors such as

                C _ E _ I _ A _ S
       (as found in this leafy Virginia
       T _ _ A _ _ O plant)

        and

harmful R _ _ I _ T _ O _
(such as from the sun)

all increases gene mutations and thus increases the chance of cancer.

(3) Examples of types of radiation that causes mutations are

S _ _ _ I _ _ T (see above),

_ - R _ _ _ ,

(Not that cartoon characters like Homer
here have anything to worry about except
Bart.)

& N _ _ _ E _ R Radiation.

(4) Examples of chemicals that cause mutations are

A _ B _ _ T O _ ,
(as removed quite a few years ago from some
of Shenendehowa school buildings.)

& P E _ T _ _ I D _ S such as sprayed
from crop dusting planes and farm
machinery.

(5)

        Mutations can be passed on to offspring
   only when they occur in the DNA of
   _ _ _ cells (G _ _ E _ _ S   such as
   O _ _ M or _ P E _ M).

If mutations occur in any other types of cells (non-sexy ones of course), they can be passed on only to other _ O _ Y cells.

Click here for your answers.

F. Gene Mutation Diseases (NOTE -- Back to italics for Bio H)

        Topic “F” is required only for Biology H students.
        This is interesting disease material, so Bio R students, if you get done early,
        continue on.

F. Some diseases of humans are caused by gene mutations. Let's learn a few.

Disease (1)

            This disease if   H _ _ O _ Y _ _ U _ (the two
       genes for this disease are the same) results in
      deterioration (down fall) of the N _ _ _ O _ S
    system as pictured on the left.

A child with this disease normally dies
by the age of four.

            Since this disease is fatal in childhood,
      the parents could not have had two
      harmful genes. Each must have had only
      _ _ _ gene for this disease and their
      second gene was normal.

            Such parents, as shown on the chart on the
    left, which hide the one bad gene are
    known as C _ _ _ I _ R _ of this disease.

    (Here's a clue!)

Some of the symptoms of this disease were first described in the medical literature in the late 19th century by Dr. Warren Tay (British) and
Dr. Bernard Sachs (US).

Name the disease. T_ Y S _ _ H S DISEASE

If you want to learn much more about this disease,
click on ... http://www.mamashealth.com/tay.asp

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Disease (2)

This disease if homozygous results in the
inability to break down a protein subunit
(_ M _ _ O _ C _ D) named
Phenylalanine found commonly in our diet.

In this diagram, the enzyme is blocked, so the phenylalanine can't be changed into the amino acid tyrosine.

        This phenylalanine then slowly builds up
   to toxic levels and gradually retards
   _ R _ I _ development. (See photo!)

A blood test at birth quickly tells
the doctor if the child has this disease.

                                                                                                                                                                 Of course, if you greatly reduce phenylalanine
      from the diet during development, then
     the person's with this disease develops
     normally. The diet may be boring, but
    the child can then develop normally.
        Many common products have phenylalanine
    in them and are so marked if you look.

This person on the left had a normal diet and I
hear a pretty good IQ.

This disease is named for both the amino acid which builds up in the blood affecting the brain and the toxic ketones (a type of chemical) found in afflicted children or adults.

Name the disease. P _ _ short for (P _ E _ _ L K _ _ _ U _ _ A)

If you want to learn much more about this disease, click on ... http://www.medhelp.org/lib/pku.htm

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Disease (3)

In a normal person, here's the structure
of red blood cells (r.b.c.).

          This group of cells is tightly packed
     together and does not have fluid
     between them.

            This disease if homozygous results in
    blood cells that can not maintain their
    normal shape.

Here about half the r.b.c.'s are normal
and