Module 3

Sun Protection

Protection from exposure to ultraviolet (UV) radiation in sunlight is important, especially during childhood and adolescence.

(03.06) Down syndrome is a genetic disorder that is also called trisomy 21. A person with Down Syndrome has an extra copy of chromosome 21. What can you infer is most likely the genetic mutation that results in Down syndrome? A Nondisjunction during meiosis B. Complete duplication of chromosomes during polyploidy C. Translocation during genetic replication D. Crossing over during meiosis

A Nondisjunction during meiosis

Define Mutation

A change in a cell's genetic material

(03.03) In pea plants, the allele for tall plants is dominant to the allele for short plants. If a homozygous tall plant is crossed with a homozygous short plant, what percent of offspring would you expect to be short? A. 0 percent B. 25 percent C. 50 percent D. 100 percent

A. 0 percent

(03.04) The pedigree chart below shows the individuals in a family who exhibit a certain trait. Based on the information in the chart, what are the chances that a second child born to couple 4−5 in the third generation will show the trait? A. 25 percent B. 50 percent C. 100 percent D. 0 percent

A. 25 percent

(03.08) Hemophilia is an linked recessive disease. Under which of the following conditions will a female child inherit hemophilia? A. Both parents must have the hemophilia allele. B. Only the father must have the hemophilia allele. C. Both sets of grandparents must have the hemophilia allele. D. Only the mother must have the hemophilia allele.

A. Both parents must have the hemophilia allele.

Genetic Engineering

the deliberate modification of the characteristics of an organism by manipulating its genetic material. - the use of such technology is accompanied by ethical questions: some question whether we have the right to change an organism's genetic makeup, while others worry that doing so may have future consequences, such as limited biodiversity and impacts on evolution.

independent assortment

One of Mendel's principles that states that genes for different traits can segregate independently during the formation of gametes

Reproduction: Sexual

- A form of reproduction in which an offspring is formed from the combination of two gametes, one from each parent - Two parents - Diverse offspring - Usually slower, but diversity helps ensure survival of the species

Reproduction: Asexual

- A form of reproduction in which new individuals are formed from one parent without the involvement of gametes. - One parent - Identical offspring - Quick, produces large number of offspring

Punnett Square - Monohybrid cross

- A genetic cross using a single trait. - prefix mono = one Example: see picture

Punnet Square - Dihybrid cross

- A genetic cross using two different traits - prefix di = two Example: see picture

Biotechnology - Transgenic

- An organism with traits produced by recombinant DNA. Examples: - modification in agriculture that uses genes from bacteria that produce a protein known as Bt toxin - resistance to infections - add nutritional value

Cancer

- Caused by genetic or environmental conditions, or a combination of the two. - A disorder in which body cells lose the ability to control cell growth - As a result, the cells divide uncontrollably - These type of cells can form a mass of cells called a tumor.

Mitosis - Anaphase

- Centromerers holding sister chromatids divide and individual chromosomes are pulled apart - Chromosomes move along the spindle fibers to opposite ends of the cell

Gene Mutations

- Chemical changes one or a few nucleotides that occur at a single point within a gene. - Usually occur during DNA replication before a cell divides Types: Base - Pair substitutions Base - Pair Insertions and Deletions

Mutation - Deletion

- Chromosmal Mutation - Involves the loss of all or part of a chromosome

Mutation - Translocation

- Chromosomal Mutation - A part of one chromosome breaks off and attaches to another chromosome

Mutation - Duplication

- Chromosomal Mutation - Produces an extra copy of all or part of a chromosome

Mutation - Inversion

- Chromosomal Mutation - Reverses the direction of parts of a chromosome

Meiosis - Prophase 2

- Chromosomes are still paired together as sister chromatids - Spindle fibers begin to form

Prophase

- Duplicated chromatin condenses - The nuclear membrane and the nucleolus disappear - Spindle fibers begin to form

Meiosis - Telophase 1

- Each pole has a haploid set of chromosomes, but each chromosome still has 2 chromatids

Meiosis - Prophase 1

- Each set of sister chromatids pair up with it's homologous pair forming a set of 4 chromatids

DNA Replication: Structure of DNA - Hydrogen Bonding

- Form between the nitrogenous bases of each strand, providing just enough attraction to hold the two strands together. - This is important because if the two strands were held together by strong covalent bonds, the strands would be very difficult to separate; the ability to separate the two strands of DNA is essential to the molecule's function.

Mendel - Homozygous

- Having identical alleles for a given gene, such as AA or aa. - Greek prefix: homo = same

Mendel - Heterozygous

- Having two different alleles for a given gene, such as Aa . - Greek prefix: hetero = different

Meiosis - Metaphase 1

- Homologous sets line up in the middle of the cell - Spindle fibers attach

Meiosis - Telophase 2

- Nuclear membranes form around each haploid set of chromosomes

Mutation - Base - Pair insertions and Deletions

- Occur when nucleotides are added or removed from the DNA sequence

Mutation - Base - Pair Substitutions

- Occurs when one base pair (a nucleotide on one strand of the DNA molecule and its partner from the complementary strand) are replaced with a different pair of nucleotides.

Cytokinesis

- Once the genetic information is duplicated and split into two different nuclei, this phase splits the division process by splitting the cell in two - The division of the cytoplasm, organelles, and other material contained within the cell. - It differs in Plant and Animal cells

Mutagens

- Physical or chemical agents that interact with DNA to cause mutations - Physical types include some forms of electromagnetic radiation such as X-Rays and Ultraviolet (UV) light. - Chemical type examples include certain pesticides, tobacco smoke, and environmental pollutants.

What are considered drugs?

- Prescription drugs, over the counter drugs, alcohol, tobacco, stimulants, steroids, and hallucinogens

Meiosis and crossing over

- Process in which homologous chromosomes exchange portions of their chromatids during meiosis. - During this process in Prophase 1, sister chromatids within each tetrad attach and swap portions of adjacent DNA molecules. - Neither chromatid gains or loses any genes, but this crossing over increases the genetic variation in the sex cells.

Meiosis - Anaphase 2

- Separate sister chromatids are pulled to opposite sides of the cell

Mitosis - Metaphase

- Sister chromatid pairs line up across the middle of the cell - Spindle fibers attach to the centromeres

Meiosis - Metaphase 2

- Sister chromatid pairs line up in the middle of the cell - spindle fibers attach at middle of each pair

Meiosis - Anaphase 1

- Spindle fibers pull chromosomes apart, however sister chromatids remain attached

Cytokenesis in animal cells

- The cell membrane is pulled inward until the cell is pinched in two. - Each new daughter cell contains its own nucleus and organelles

Meiosis - Cytokinesis

- The cell splits into two daughter cells - Due to crossing over in prophase 1, the two daughter cells produced by meiosis have different sets of chromosomes from each other and the cell that entered meiosis.

Mitosis - Telophase

- The condensed chromosomes stretch out - Nuclear membranes form around each set of chromosomes - Spindles break apart

Genotype

- The genetic make-up of an organism, including the two alleles it possesses for given genes. - Greek prefix: gen = gene

Genetic Factors

- The mixing of genes through sexual reproduction is beneficial to a population because it created diversity - A person's health is influenced by the combination of genes inherited from the parents

Phenotypes

- The observable physical or biochemical traits of an organism, as determined by genetic makeup. - Greek prefix: pheno = show or bring to light

Meiosis

- The process where a single cell divides twice to produce four cells containing half the original amount of genetic information. - One cell divides twice to form four daughter cells. - Phases include; Prophase 1 Metaphase 1 Anaphase 1 Telophase 1 Cytokinesis Prophase 2 Metaphase 2 Anaphase 2 Telophase 2

Infectious Disease

- These can be cause by pathogens such as viruses, bacteria, fungi and protists or parasites - Some spread through coughing, sneezing, exchange of bodily fluids, or other physical contact. Others are spread through contaminated water or food, or by infected animals.

Punnett Square

- use mathematical probability to help predict the likelihood of possible genotype combinations in offspring. - If the parent is heterozygous dominant, approximately half the offspring will have the dominant trait and half the recessive trait. - If the parent is homozygous dominant, all the offspring will have the dominant trait and none will exhibit the recessive trait.

How do viruses spread?

- viruses are nonliving pathogens that replicate by inserting their genetic material into a host cell and taking over the host cell's function. - Many viruses can spread from person to person through coughing or sneezing, or bodily contact. - Hand washing, vaccinations, and other important preventative measures are important minimize the spread of these diseases

(03.03) In fruit flies, the allele for vestigial wings is recessive to the allele for normal wings. In a generation of fruit flies, 18 males and 15 females with vestigial wings are produced, and 43 males and 44 females with normal wings are produced. Which of the following is the best conclusion you can make about the parents of this generation? A. Both parents were heterozygous for wing type. B. One parent was heterozygous for wing type and the other was homozygous with normal wings. C. Both parents were homozygous with normal wings. D. One parent had vestigial wings and the other was heterozygous for wing type.

A. Both parents were heterozygous for wing type.

(3.02) During meiosis, the chromatids of homologous chromosomes have just undergone crossing over. Which of the following phases will the cell enter next? A. Metaphase I B. Anaphase II C. Prophase II D. Telophase I

A. Metaphase I

(03.05) While mRNA strands are being created a sequence is sometimes miscopied. What is the best possible outcome for the cell should this take place? A. The miscopied sequence codes for the same amino acids as the original sequence. B. The new sequence creates a protein that serves a different function from the original. C. The ribosomes will correct the mistake before the tRNA matches an amino acid to it. D. The mRNA will only be used to create non-critical proteins for the cell.

A. The miscopied sequence codes for the same amino acids as the original sequence.

(03.08) After a natural disaster, aid agencies typically make providing clean drinking water a priority. Why would water be a priority when most victims have major problems, such as the loss of a home, to deal with? A. Water sources can get contaminated and infect large groups of people. B. Water systems must be turned off during all disasters. C. Water is an easier problem to solve the crisis. D. Water is something most people forget about during a crisis.

A. Water sources can get contaminated and infect large groups of people.

Mendel - Dominant

An allele for a trait that tends to be expressed in the phenotype and mask the expression of a recessive allele.

Mendel - Recessive

An allele for a trait that will not be expressed in the phenotype unless the organism is homozygous for the trait.

(03.07) Recently, some crop plants were genetically modified to be immune to the effects of weed killers. Which of the environmental concerns should be considered before planting the resistant crops? A. An increase in crop diversity B. A decrease in crop diversity C. An increase in crop yield D. A decrease in crop yield

B. A decrease in crop diversity

(03.05) Which of the following best explains how the structure of DNA determines the structure of proteins? A. The genes contain the instructions to make DNA, which is used to synthesize proteins. B. Cells contain DNA, which is made up of genes that contain the instructions to make proteins. C. DNA is a segment of a gene that contains the code to synthesize proteins. D. The DNA in proteins make up cells that contain the code that determine the structure of DNA.

B. Cells contain DNA, which is made up of genes that contain the instructions to make proteins.

(03.05) DNA replication is a process that involves copying the DNA molecule. If a single base was miscopied, what would be a possible result of this for the cell in which it happened? A. All the proteins the cell creates from the miscopied strand will do different jobs than the old ones. B. If the new sequence codes for the same amino acid as the original cell, it will function normally. C. Both new DNA strands will end up together in a new cell, and the inaccurate one will be discarded. D. Any miscopied DNA will be replaced with an accurate DNA copy once the cell divides.

B. If the new sequence codes for the same amino acid as the original cell, it will function normally.

Mitosis vs. Meiosis: Importance

Mitosis: Production of diploid body cells for growth and repair. Meiosis: Production of haploid gamete cells for sexual reproduction

(03.04) A plant breeder found a species of flowering plant with very attractive flowers growing wild in a field and she thought it would appeal to her customers. Some of the plants of this species had red flowers, some white flowers, and some pink flowers. While she would like to be able to offer her customers all three colors of flowers, she only has permission from the landowner to dig up one plant to bring back to the nursery as breeding stock. What would be the best thing for her to do? A. Take a white flowering plant since the white allele could be masking the pink allelle. B. Take a pink flowering plant since it is likely to carry both the red and white alleles. C. Take a red flowering plant since it could produce all three colors eventually. D. Take a red flowering plant since the red allele is likely the dominant one.

B. Take a pink flowering plant since it is likely to carry both the red and white alleles.

(03.03) Codominance is a form of inheritance in which two different alleles for a gene are both expressed, and neither allele is dominant over the other. One example of codominance is fur color in cattle; the alleles for red fur and white fur are codominant. If a homozygous red cow and a homozygous white bull mate, what would you expect to find in their offspring? A. They will all have white fur. B. Their fur will be a mixture of red and white hairs. C. Their fur will be pink. D. They will all have red fur.

B. Their fur will be a mixture of red and white hairs.

(03.02) In which scenario would mitosis be least desirable in terms of a species' survival? A. A species has little energy to devote to reproduction. B. A species is unable to travel far to find a mate. C. A species has to adjust rapidly to a changing environment. D. A species is preyed upon by numerous successful predators.

C. A species has to adjust rapidly to a changing environment.

(03.01) In a cell that is undergoing mitosis, sister chromatids have aligned along the cell's equator, and spindle fibers have attached to the centromeres of the sister chromatids. Which of the following processes will the cell enter next? A. Metaphase B. Telophase C. Anaphase D. Prophase

C. Anaphase

(03.01) A body cell is in the longest stage of its life cycle. The cell grows, synthesizing proteins and increasing in size. Eventually, the cell will grow too large to carry out normal activities and begin mitosis. Which phase is the cell in? A. G2 B. Cytokinesis C. G1 D. S

C. G1

(03.02) A wolf's diploid number of chromosomes is 78. How would the number of chromosomes in the wolf's body cells compare to the number of chromosomes in its gametes? A. Its body cells and gametes would both have 39 chromosomes. B. Its body cells would have 39 chromosomes, and its gametes would have 78 chromosomes. C. Its body cells would have 78 chromosomes, and its gametes would have 39 chromosomes. D. Its body cells and gametes would both have 78 chromosomes.

C. Its body cells would have 78 chromosomes, and its gametes would have 39 chromosomes.

(03.06) If a mutation occurs in a gamete, which of the following is most likely to result? A. If the mutation occurs on a recessive gene, it will most likely be expressed. B If the mutation is non-disjunctive, then it will not be passed on. C. The mutation will not always cause the offspring to be genetically disadvantaged. D. The mutation will not be passed on to the offspring.

C. The mutation will not always cause the offspring to be genetically disadvantaged.

G2 Phase

Cell grows and makes final preparations for cell division (preparation for Mitosis)

G1 Phase

Cell grows in size and performs its particular job and function. (Cell Growth)

S Phase

Cell makes copy of the chromatin in the nucleus. (DNA Replication)

Chromosomal Mutations

Changes in the number or structure of chromosomes Types: Deletion Duplication Inversion Translocation

(03.06) Which of the following mutations would most likely be identified as a chromosomal translocation? A. A mutation occurs while copying a chromosome. Instead of reading EFGHI, the chromosome reads EFGFGHI. B. The genetic sequence is MNOPQ. A mutation occurs and the sequence of bases that encodes for gene N is not copied. C. The sequence of bases on the mRNA reads CUU and codes for the amino acid leucine. A mutation occurs and the mRNA sequence changes to CCU and now codes for the amino acid proline. D. A sequence of bases encodes for genes XXY. A portion of another chromosome breaks off and inserts within genes XYZ.

D. A sequence of bases encodes for genes XXY. A portion of another chromosome breaks off and inserts within genes XYZ.

(3.05) Why must cells be able to both transcribe and replicate their DNA? A. The cell's DNA must be transcribed before it can be replicated. B. New cells can be created only after transcription has taken place. C. Transcription can be used when a cell is unable to replicate. D. Replication creates new DNA, while transcription creates mRNA.

D. Replication creates new DNA, while transcription creates mRNA.

(03.05) If a tRNA molecule has an anticodon which reads AUG, what was the codon of the mRNA molecule? A. CGU B. TAC C. TAG D. UAC

D. UAC

(03.06) In the case of cancer, uncontrolled cell division is a problem because it A. lowers t-cell and lymphocyte production B. requires unreasonable hydration rates C. causes excessive white cell production D. interferes with other cell replication

D. interferes with other cell replication

Interphase has 3 phases

G1 Phase S Phase G2 Phase

Mitosis vs. Meiosis: Number of division cells

In Mitosis: One, consisting of prophase, metaphase, anaphase, telophase, and cytokinesis In Meiosis: Two, each consisting of prophase, metaphase, anaphase, telophase, and cytokinesis

Mitosis vs. Meiosis: DNA replication, forming sister chromatids

In Mitosis: This occurs during interphase before nuclear division begins. In Meiosis: This occurs during interphase before nuclear division begins.

Mitosis vs. Meiosis: Total number of daughter cells

In Mitosis: Two diploid cells, genetically identical to the parent cell In Meiosis: Four haploid cells, containing half as many chromosomes as the original parent cell

Substance Abuse

Intentional inappropriate use of drugs, repeatedly and willfully using a drug in ways other than how they are prescribed or socially accepted.

The Cell Cycle is split into two main parts:

Interphase and Cell Division

Exercise and Diet

Lifestyle factor that lowers a person's risk of becoming obese and developing related diseases

Cell Division has 2 phases

Mitosis Cytokinesis

Mitosis

The cell distributes the genetic material into 2 separate nuclei during 4 phases: Prophase Metaphase Anaphase Telophase

Meiosis - Cytokinesis (2)

The cells divide, forming a total of 4 haploid daughter cells from the original diploid cell that entered meiosis 1

DNA Replication: Translation

The process in which the base sequences in mRNA are used to direct the arrangement of amino acids in protein synthesis. Steps: - A ribosome attaches to an mRNA molecule in the cytoplasm - As each codon passes through the ribosome, tRNA brings the corresponding amino acid into the ribosome.

DNA Replication: Transcription

The synthesis of an RNA molecule from a DNA template. Steps: - First, the RNA polymerase binds to a DNA molecule and separates its two strands. - One strand of the DNA serves as a template to assemble nucleotides together into a complementary mRNA strand. - Specific base sequences on the DNA molecule signal where the RNA polymerase should begin transcribing a section of mRNA and other base sequences on the DNA, then signal stop.

How are some diseases inherited?

They can be inherited by the alleles passed down by one or both parents

Why is water so important? How are infectious diseases spread by contaminated water and food?

This is important, because some microorganisms, especially those that infect the digestive tract, are spread through water contamination. Infectious diseases spread because we eat fish that comes from water, and contaminated water can pass microorganisms onto fruits and vegetables that we eat. (in recent years several disease outbreaks have been traced back to packaged lettuce and other produce).

Biotechnology - Cloning

Uses a single cell from an adult organism to grow an entirely new individual that is genetically identical to the original organism