Download Mrs. Paparella/ Living Environment Genetics Essential Questions

Mrs. Paparella/ Living Environment
Genetics Essential Questions
Genetics Unit Essential Questions
And Answers
1. What determines an organism’s characteristics?
Each chromosome in the nucleus contains 1000’s of genes for the traits (characteristics) that an
organism shows. Chromosome pairs carry genes for the same trait. We have 2 alleles for each gene.
(you get one allele from each parent)
2. How many chromosomes do humans have?
We have 46 chromosomes or 23 homologous pairs of chromosomes. 22 pairs are called autosomes
and the 23rd pair is called the sex chromosomes. They can be X or Y.
3. What determines the sex of a person?
XX is a female and XY is a male. The X and Y chromosomes are found in the gametes (sex cells). The
egg nucleus contains 22 + X and the sperm nucleus contains 22 +X or 22 + Y. (1n). The union of sperm
and egg restores the number of chromosomes to 46 (2n).
4. What is the difference between the monoploid and diploid number of chromosomes?
Monoploid (or haploid) is the 1n number of chromosomes found in sperm or egg cells. Diploid is the
2n number of chromosomes found in all body cells. We have 46 chromosomes so,
n or 1n =23;
2n =46 ; fruit flies have 8 pairs of chromosomes: 1n=4 and 2n=8 The sperm and egg each contribute ½
the number of total chromosomes.
5. What makes up DNA?
DNA is made up of many nucleotides. [Russian biochemist Phoebus Levene discovered the nucleotide
make up.] A nucleotide contains 3 things:
1) a sugar (deoxyribose)
2) a phosphate group (PO4 ion)
3) a nitrogen base pair (A , T, G, or C) [A binds with T, G binds with C in the complementary strand;
this matching sequence was discovered by Erwin Chargaff]
6. What is the shape of DNA?
DNA is a double helix (twisted ladder). Watson and Crick are credited with the discovery of the shape
of DNA in the 1950’s, but Rosalind Franklin did important work in X-ray crystallography to help them
discover the shape. DNA was first identified in the late 1860s by Swiss chemist Friedrich Miescher. The
Mrs. Paparella/ Living Environment
Genetics Essential Questions
other scientists Chargaff, Erwinn , Franklin and Levene were fundamental in laying the ground work for
the discovery of the double helix shape.
7. What does replication of DNA mean?
Replicate means to make an exact copy of itself.
8. Why is replication needed?
In order for a new cell to be formed in mitosis, a 2nd copy of the DNA is needed.
9. Why is protein synthesis necessary?
Proteins make up many different kinds of molecules (10,000) in your body. Muscle fibers, enzymes,
antibodies, hormones, hair, skin and nails are all made up of proteins. Proteins make up 15% of your
total body mass. Proteins are involved in cell communication as neurotransmitters and chemical
messengers and control cell growth and many reactions in your body.
10. What is the relationship between DNA, chromosomes, genes, ribosomes and protein synthesis?
DNA makes up genes. Genes make up chromosomes. The genes in DNA have a specific code (Nitrogen
base order: AAGTTCAGAAT (for example) which determines the order of amino acids that will be
brought to the ribosome to make the protein in the process of protein synthesis.
11. What are the steps to protein synthesis?
1. DNA is transcribed into mRNA (messenger RNA) in the nucleus. A-->U; G-->C; T-->A
2. mRNA leaves the nucleus and goes to the ribosome in the cytoplasm.
3. tRNA (transfer RNA)[with its anticodon set of 3 letters] brings the specific amino acid to
the mRNA[ with its codon set of 3 complementary letters] at the ribosome and translation occurs. The
amino acids are joined together to form a specific protein with a specific and unique shape that
determines its function.
DNARNAPROTEIN SHAPE TRAIT (FUNCTION)
TRANSCRIPTIONTRANSLATIONPROTEIN TRAIT
12. What are mutations and how are they caused?
Mutations are any changes in the normal genetic code of an organism. There are different types of
mutations: substitutions, deletions, additions. There can be several different causes of mutations.
Mutagenic Agents include any environmental factors such as exposure to X-rays or other types of
radiation such as strong UV (ultra violet) rays, nuclear radiation, chemical exposure such as pesticides
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Genetics Essential Questions
or herbicides or chemicals used in manufacturing such as lead or mercury or biological agents such as
viruses.
13. Why are mutations bad?
Mutations change the amino acid sequence of proteins. If the shape of the protein is changed, it won’t
work properly and homeostasis is disrupted.
14. What are Chromosome mutations?
Chromosome mutations are inherited. You can have too many or not enough chromosomes. Most of
these are fatal.
15. What is an example of a non-lethal mutation?
Down’s Syndrome is non-lethal. It is caused by inheriting an extra #21 chromosomes. People with
Down’s Syndrome have delays in mental and physical development.
16. What are 4 examples of Genetic Technologies?
A. Selective Breeding
B. Genetic engineering
C. Karyotyping
D. Gel Electrophoresis
17. What is the definition of and give 4 examples of Selective Breeding?
Selective breeding is when you breed specific organisms to produce offspring that have desired traits.
For example: breeding cows to produce greater amounts of milk or milk with a higher or lower fat
content; breeding horses to produce a faster race horse or a stronger work horse; breeding tomatoes
that have a longer shelf-life or better flavor or higher resistance to disease; breeding orange trees to
produce sweeter or bigger oranges.
18. What is outbreeding or Cross breeding?
Crossing 2 slightly related species to produce offspring that have a desired trait.
Ex: female horse x male donkey = mule; The mule is sterile. The AMA is the American Mule
Association. “A primary objective of the AMA is the promotion of the modern mule as highly
intelligent, versatile and personable riding companion. The AMA also promotes the Donkey which is an
integral component in the genetic makeup of the mule.”
Ex: lion x tiger = liger; zebra x horse = zorse
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Genetics Essential Questions
19. What is done in genetic engineering and what are 2 examples of its use?
Genetic engineering involves the cutting out of a gene from one organism (using restriction enzymes)
and inserting it into another organism’s DNA (with the help of enzymes) so that the second organism
( usually a bacteria) can be a factory for quickly producing a specific product. The products would
include specific proteins/ specific enzymes or hormones. Insulin is produced on a wide-scale as well
as Human Growth Hormone by using bacteria with those specific DNA strands inserted into them that
code for insulin or HGH.
20. How and why is karyotyping a genetic technology?
Karyotyping is done by taking a DNA sample from a person or fetus (using amniocentesis). Making
pictures of the chromosomes and then matching them up in their pairs to look for any extra
chromosomes or missing pieces of chromosomes. It is used to diagnose whether a person has a
specific genetic condition or disorder.
21. What is Gel Electrophoresis and why is it useful?
Gel electrophoresis is a technique used to compare DNA evidence in order to identify people. Specific
bands of DNA with specific patterns are formed in the testing process. Restriction enzymes are used to
cut the DNA at specific sections.
Forensic science uses it to analyze crime scene evidence and make matches between suspects or
eliminate someone as a suspect. It can also be used for paternity testing or sibling matching.
Biologists can use it to compare species and trace ancestry/evolutionary relationships.