NAME:
Regents Biology
Homework Packet
Unit 7: Genetics
· Use your Biology by Miller & Levine textbook to complete and help with the following homework assignments.
· (1) Read the assigned pages, (2) Define the vocabulary, and (3) Answer the questions.
· Neatness counts. Number the definitions. Write the page and number of the questions. Do your work in ink or even type the homework. Staple the definitions and questions to the HW packet.
· The homework assignment is due the day before the test. We will use the HW packet as a test review. The completed and corrected HW packet will be collected on the day of the test. Late homework assignments receive no credit (0). If the assignment is not turned in by the last day of the quarter the zero grade (0) will change to -5.
Chapter 11: Introduction to Genetics
Read pages 306 – 335
p. 308 Vocab (9)
p. 313 Vocab (7)
p. 319 Vocab (4)
p. 312 #1b, 2a, 2b, 2c, 3
p. 318 #2a, 2b, 4
p. 321 #2a
p. 329 #4a, 4b
Regents Review:
Pgs. 332 – 335
#1 – 33
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Chapter 12: DNA
Read pages 336 – 359
p. 338 Vocab (2)
p. 344 Vocab (1)
p. 350 Vocab (3)
p. 343 #3a, 3b
p. 348 #1b
p. 353 #1a, 2b
Regents Review:
Pgs. 356 - 359
#1 – 36
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Chapter 13: RNA and Protein Synthesis
Read pages 360 – 389
p. 362 Vocab (9)
p. 366 Vocab (6)
p. 372 Vocab (5)
p. 377 Vocab (7)
p. 365 #1a
p. 371 #2b, 3b
p. 376 #1b
p. 383 #2a
Regents Review:
Pgs. 386 – 389
#1 – 34
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Chapter 14: Human Heredity
Read pages 390 – 415
p. 392 Vocab (6)
p. 398 Vocab (1)
p. 403 Vocab (4)
p. 397 #1b, 2a, 2b, 3a
p. 401 #2b
p. 409 #2a, 3
Regents Review:
Pgs. 412 – 415
#1 – 33
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Chapter 15: Genetic Engineering
Read pages 416 – 445
p. 418 Vocab (4)
p. 421 Vocab (6)
p. 428 Vocab (4)
p. 420 #2a
p. 427 #1a, 2a
p. 434 #2a, 3b
p. 439 #4
Regents Review:
Pgs. 442 – 445
#1 – 35
Genetics Review
MENDELIAN GENETICS:
______ (1822 – 1884) – Austrian monk;
· Developed some basic principles of heredity without any knowledge of genes or chromosomes.
· Used a mathematical analysis of large numbers of offspring produced by crossing pea plants to develop major concepts of genetics.
· As a result of analyzing specific mathematical ratios associated with certain characteristics in the offspring, Mendel proposed that characteristics were inherited as the result of the transmission of hereditary factors.
· Mendel observed contrasting characteristics in pea plants in his work: flower color is purple or white; flower position is axil or terminal; stem length is long or short; seed shape is round or wrinkled; seed color is yellow or green; pod shape is inflated or constricted; pod color is yellow or green
Major Genetic Concepts:
1. ______= a pattern of heredity in which only one gene of an allelic pair is expressed. In the heterozygous condition, one allele of a gene may express itself and mask the presence of the other allele.
ex. Toe Size T = long toes, t = short toes à Tt x Tt.
dominant trait: the trait or allele that is expressed
recessive trait: the trait or allele that is present but that is not expressed
2. ______= When gametes are formed during meiosis there is a random segregation of homologous chromosomes. As a result of fertilization, alleles recombine. As a consequence, new allelic gene combinations are likely to be produced. Segregation and recombination is illustrated by the cross between two individuals heterozygous for a trait.
3. ______= If the genes for two different traits are located on different chromosomes (nonhomologous chromosomes), they segregate randomly during meiosis and, therefore, may be inherited independently of each other. The cross of two organisms heterozygous for a trait is known as a hybrid cross.
Assuming large numbers of such crosses:
· the phenotypic ratio of dominant offspring to recessive offspring is 3:1
· the genotypic ratio of homozygous dominant offspring to heterozygous dominant offspring to homozygous recessive offspring is 1:2:1
Other Forms of Inheritance
1. ______: A case of contrasting alleles in which one allele is only partially dominant over the other; the dominant allele is only partially expressed when the recessive allele is present.
§ red flowers X white flowers = pink flowers
2. ______: a case of contrasting alleles in which neither allele is dominant; over the other (alleles have equal power)
§ cross between red cattle X white cattle = roan cattle (cattle with red and white hairs).
3. ______: Not every trait is controlled by just two different alleles. Some traits have more than two different alleles, but an organism can only carry two of the alleles.
§ in humans there are 3 different alleles for blood groups IA, IB, i
4. ______: alleles that are carried on the sex chromosomes (X or Y). Generally traits carried on the X chromosome are more likely to occur in males than females because males only have one X chromosome so which ever allele (dominant or recessive) occurs on the X chromosome is expressed in the phenotype.
§ color blindness and hemophilia
Gene Linkage: when genes for two different traits (nonallelic genes) are located on the same chromosome pair (homologous chromosomes); Linked genes are usually inherited together.
Crossing Over: during synapsis in the first meiotic division, the chromatids in a homologous pair of chromosomes often twist around each other, break, exchange segments and rejoin; Crossing over results in the rearrangement of linked genes and increases the variability of offspring.
Karyotype: an enlarged photograph of the chromosomes in an organism; Human diploid cells contain 23 pairs of chromosomes. Autosomes = body chromosomes (22 pr. in humans) One pair of sex chromosomes. In the male each sex chromosome is unlike and is designated XY. In the female each sex chromosome is alike and is designated XX. The sex of a human is genetically determined at fertilization when a sperm cell containing either an X or a Y chromosome unites with an egg cell containing an X chromosome
Modern Genetics:
Nucleic Acids: polymer of nucleotides;
1. _____ (ribonucleic acid) directs cellular protein synthesis; found in ribosomes & nucleoli
2. _____ (deoxyribonucleic acid) contains the genetic code of instructions that direct a cell's behavior through the synthesis of proteins; found in the chromosomes of the nucleus (and a few other organelles); Chromosomes found in the nucleus carry the hereditary material; DNA controls cellular activity by influencing the production of enzymes.
Watson and Crick (early 1950's): determined the structure of the DNA molecule; Consists of two chains of nucleotide units in a twisted ladder-like structure = double helix;
· The sides of the ladder are made up of alternating deoxyribose sugar and phosphate group units;
· The rungs of the ladder are made of 2 nitrogenous bases per rung linked together by a weak hydrogen bond.
· Only 2 combinations of base pairs can form the rungs of the DNA molecule; Adenine - Thymine (A-T); Guanine - Cytosine (C-G)
Look up Rosalind Franklin…What did she have to do with DNA?
Structure of DNA Molecules: DNA is a very long chain polymer made up of thousands of repeating units called nucleotides. Nucleotide Unit is composed of a phosphate group, a sugar, and a nitrogenous base.
§ The Nitrogenous Bases are; adenine (A) thymine (T)guanine (G) cytosine (C)
§ Nucleotide = subunit of DNA
§ Gene = specific sequence of nucleotides that codes for a polypeptide. Genes can range from 10,000 –
§ 100,000 base pairs
§ Chromosome = a collection of genes and “junk DNA” connected together. The DNA is then wrapped around proteins to pack it into the nucleus. Chromosomes are millions of base pairs long. Every organism has a specific chromosome number - diploid = 2n.
§ RNA = is also a polymer formed by a sequence of nucleotides.
§ The RNA molecule is a SINGLE nucleotide strand, not a double strand as in DNA.
§ The sugar molecule in RNA is RIBOSE - not deoxyribose as in DNA.
§ The base URACIL (U) takes the place of thymine (T)
§ Types of RNA: (1) mRNA (messenger RNA) made in nucleus; (2) tRNA (transfer RNA) on
the ribosomes; (3) rRNA (ribosomal RNA) in the cytoplasm
DNA Replication:
1. The double stranded DNA molecule unwinds and unzips between the weak hydrogen bonds between the nitrogenous base pairs.
2. Free nucleotides present in the nucleus attach themselves by forming new hydrogen bonds with the exposed bases in the single chain. The only base which can reattach is the same type of base that was originally joined to it.
Usefulness of the Watson-Crick Model
1. Explained how mitosis produces exact DNA copies
for each daughter cell à thus the genetic information passes on unchanged.
2. Explained how DNA acts as a code directing the making of enzymes and other proteins by a cell, thus directing cellular activities.
Protein Synthesis: is a 2 step cellular process to make proteins. DNA contains the instructions for the order of amino acids in a protein. The ribosomes in the cell put the amino acids together in the order the DNA dictates.
Analogy: DNA = Recipe; Ribosome = baker; Protein = cake
A) Transcription = transfer of the genetic message from DNA to mRNA;
1. DNA serves as a template for the synthesis of mRNA from free RNA nucleotides in the nucleus.
2. mRNA molecules carrying a specific code determined by the base sequence of the DNA template moves
from the nucleus to the cytoplasm.
3. Strands of mRNA carrying codons transcribed from DNA, move to the ribosomes in the cytoplasm. (each
codon will code for a specific amino acid)
B) Translation = transfer of the genetic message into amino acid sequence
4. mRNA strands become associated with rRNA on the ribosomes.
5. Different anticodons of nitrogenous bases in tRNA molecules pick up specific amino acids in the cytoplasm
and carry them to mRNA at the ribosomes.
6. Amino acids are put into position on the ribosome with instructions from the anticodon codes of tRNA and
mRNA.
7. With the aid of enzymes and ATP (energy), the amino acids are bonded to form a polypeptide chain
(protein) on the ribosome.
8. This protein formation is what directs metabolic activity in any cell.
One gene codes for one polypeptide chain.
Since the sequence of nucleotides in DNA determines the sequence of nucleotides in messenger RNA, DNA ultimately determines the sequence of amino acids in specific proteins. The specificity of enzymes is dependent on their protein makeup, and, since the individuality of a cell is largely a function of the enzymes it
possesses, it is evident that DNA determines the individuality and function of an organism.
The work of a cell is carried out by the many different kinds of molecules it assembles, mostly proteins. Proteins are long, folded molecules made up of up to 20 different kinds of amino acids which interact to produce specific protein shapes.
The specific shape of the protein determines the specific function of that protein.
Offspring resemble their parents because they inherit similar genes that code for the production of proteins that form similar structures and perform similar functions.
How are cell functions regulated:
1.Gene regulation allows only the selective expression of certain individual genes.
2. The regulation of certain genes controls the activity and production of certain proteins.
All this gene regulation allows cells and organisms to respond to their environment and control their growth and division. Body cells of an individual can be very different from each other, even though they have descended from a single cell (zygote) and have essentially the same genetic instructions. This is because different parts of these instructions are used in different types of cells, influenced by the cells environment and developmental history.
Genetic Research:
1. Cloning: producing a group of genetically identical offspring from the cells of an organism
This technique shows great promise in agriculture. Plants with desirable qualities can be rapidly produced from the cells of a single plant.
2. Genetic engineering: (recombinant DNA) transfer of genetic information from one organism to another; includes the transfer of entire genes and gene splicing; A cell can synthesize a new chemical coded for by its new gene(s); examples include interferon, insulin, and growth hormone.
Genetic engineering can correct genetic defects & produce agriculturally more efficient plants and animals.
Gene Therapy = correcting defective/diseases genes in cells than implanting the corrected cells back into the person; juvenile diabetes à correcting Islet of Langerhans cell; cystic fibrosis.
restriction enzymes - used to cut segments of DNA in one organism so they can be transferred into another organism; Characteristics produced by the segments of DNA may be expressed when these segments are inserted into new organisms such as bacteria. Inserting, deleting, or altering DNA segments can alter genes. An altered gene may be passed on to every cell that develops from it.
Substances from genetically engineered organisms may reduce the cost and side effects of replacing body chemicals. Human insulin produced in bacteria is already an example of this.
3. Human Genome Project: has allowed humans to know the basic framework of their genetic code; Knowledge of genetics is making possible new fields of health care.Genetic mapping is making it possible to detect and possibly correct, defective genes that may lead to poor health. A down side to this is that health insurance agencies and other organizations may use this genetic information against individuals.