Biology Quiz 3
What is cancer?
-A large family of diseases -Involve abnormal (uncontrolled) cell growth -Unregulated cell growth leads to tumors -A mass of cells that has no apparent function in the body
The centromere is a region at which: A. Sister chromatids are attached to each other B. Metaphase chromosomes align C. The tips of chromosomes are found D. The nucleus is located
A. Sister chromatids are attached to each other
An allele is a: A. Version of a gene B. Dysfunctional gene C. Protein D. Spare copy of a gene E. Phenotype
A. Version of a gene
Controls
Checkpoints at G1, G2, and metaphase determine whether a cell will be allowed to divide
Equivalent information
Each parent provides a complete set of instructions to each offspring
Metastasize
Individual cells break away and start new tumor at other locations
What factors cause quantitative variation in a trait within a population?
Multiple genes or multiple alleles influencing a trait, environmental effects that affect the expression of a trait, or a mixture of both factors.
Meiosis
form of cell division that produces specialized cells called gametes that contain half the number of chromosomes of the parent cell
Dominant
gene that masks the expression of another (recessive) allele of the same gene
Crosses with more than one gene
-Dihybrid crosses involve two traits -When genes are on different chromosomes they are placed in gametes independently of each other -In a Punnett Square of a dihybrid cross includes all possible sperm genotypes and all possible egg genotypes -Results in 16 boxes
Huntington's Disease
-Fatal genetic condition caused by a dominant allele (H) -Causes production of protein that forms clumps inside the nucleus -Brain cells involved in movement are susceptible -Cells gradually die off - progressive disease -Allele produces mutant protein that damages cells -Presence of one normal allele does not fix this (h) -Heterozygotes (Hh) exhibit symptoms -Rare condition
Mutations in single genes
-Inheritance of single genes is easier to understand -The likelihood of inheritance of these genes can be predicted -This can be done using a Punnett Square -This is a square that lists the different kinds of sperm or eggs parents can produce -Predicts the possible outcomes of a cross of the genes involved
Genetic diseases and alleles
-Most human gene alleles do not cause disease or dysfunction -Provide alternative versions to genes -Contribute to diversity among humans (appearance, physiology, behavior) -However, some alleles cause disease -Some caused by recessive alleles -Some caused by dominant alleles
'Nature' or 'Nurture'?
-What determines who we are? -Both play an important role -Cells carry instructions for all characteristics -Genotype all genetic characteristics that determine the structure and functioning of an organism; also a single gene locus to distinguish one allele or a combination of alleles, from another -Development from embryo to adult take place in a physical and social environment -Influences how genes are expressed -Phenotype physical expression of the interaction between the genotype and the environment; outward appearance and behavior of organism
Gene
-unit of genetic inheritance -in biochemistry, part of a DNA molecule that encodes a single enzyme or protein
What is the physical basis for the independent assortments of alleles into offspring? A. there are chromosome divisions during gamete production B. Homologous chromosome pairs are separated during gamete production C. Sperm and eggs are produced by different sexes D. Each gene codes for more than one protein E. The instruction manual for producing a human is complete
B. Homologous chromosome pairs are separated during gamete production
Genes
Genes as words in an instruction manual: Different words form the manual are used in different parts of the body, and identical words may be used in distinctive combinations in different cells.
What is the relationship between genotype and phenotype?
Genotype refers to the alleles you possess for a particular gene or set of genes. Phenotype is the physical trait itself, which may be influenced by genotype and environmental factors
Carcinogen
Substance that causes cancer or increases the rate of its development
Malignant
infiltrate surrounding tissues, invasive Malignant tumors can metastasize
Allele
one of several alternative forms of a gene
Cystic fibrosis
-Recessive condition -Cannot transport chloride ions into and out of cells lining the lungs, intestines and other organs -Disrupts balance of sodium and chloride in the cell -Cell produces a thick, sticky mucus -Progressive deterioration of lungs -Recurrent lung infections - e.g., Pseudomonas aeruginosa -This bacterium also produces a thick extracellular polysaccharide Normal functional chloride ion transport protein is found in cell membrane (gene - C) -In cystic fibrosis, mutant protein (gene - c) cannot get into cell membrane -If only one allele of mutant protein (Cc, heterozygous), normal function occurs -Only when have homozygous recessive condition (cc) does the disease occur
Heritability
-The amount of variation for a trait in a population that can be explained by differences in genes among individuals -Typically measured by examining correlations between groups -How similar or different are Parents and their children Siblings to each other
Scientists have recently developed a process by which a skin cell from a human can be triggered to develop into human heart muscle cell. this is possible because: A. Most cells in the human body contain the genetic instructions for making all types of human cells B. A skin cell is produced when all genes in the cell are expressed; turning off some genes in the cell results in a heart cell C. Scientists can add new genes to old cells to make them take different forms D. A skin cell expresses only recessive alleles, so it can be triggered to produce dominant heart cell alleles E. It is easy to mutate the genes in skin cells to produce the alleles required for other cell types.
A. Most cells in the human body contain the genetic instructions for making all types of human cells
Unduplicated and duplicated chromosomes
An unreplicated chromosomes is composed of one double-stranded DNA molecule. A replicated chromosomes is x-Shaped and composed of two identical double-stranded DNA molecules. Each DNA molecule of the duplicated chromosome is a copy of the original chromosome and is called a sister chromatid.
Cytokinesis (A comparison of cytokinesis in animal and plant cells)
Animal cells produce a band of filaments that tightens like a belt to pinch the cell in half. Plant cells form a cell plate down the middle of the parent cell that gives rise to the cell wall.
Sister chromatids: A. Are two different chromosomes attached to each other B. Are exact copies of one chromosome that are attached to each other C. Arise from the centrioles D. Are broken down by mitosis E. Are chromosomes that carry different genes
B. Are exact copies of one chromosome that are attached to each other
Which of the following statements correctly describes the relationship between genes and chromosomes? A. Genes are chromosomes B. Chromosomes contain many genes C. Genes are made of hundreds of thousands of chromosomes D. Genes are assorted independently during meiosis, but chromosomes are not E. More than one of the above is correct
B. Chromosomes contain many genes
Sperm and eggs in human always: A. Each have 2 copies of every gene B. Each have 1 copy of every gene C. Each contain either all recessive alleles or all dominant alleles D. Are genetically identical to all other sperm or eggs produced by that person E. Each contain all of the genetic information from their producer
B. Each have 1 copy of every gene
Cancer Detection and Treatment
Biopsy - removal of some cells, tissues or fluid to determine whether cells are cancerous Chemotherapy - use of chemicals to try to kill rapidly dividing (cancerous) cells Radiation Therapy - focusing beams of reactive particles at a tumor to kill dividing cells
Mitosis and meiosis
Both parents contribute genetic information to their offspring via their sperm and egg. The single cell that results from the fusion of one sperm with one egg contains all of the instructions necessary to produce an adult human.
Among heritable diseases, which genotype can be present in an individual without causing a disease phenotype in that individual? A. Heterozygous for a dominant disease B. Homozygous for a dominant disease C. Heterozygous for recessive disease D. Homozygous for recessive disease E. All of the above
C. Heterozygous for recessive disease
DNA polymerase: A. Attaches sister chromatids at the centromere B. Synthesizes daughter DNA molecules form fats and phospholipids C. Is the enzyme that facilitates DNA synthesis D. Causes cancer cells to stop dividing
C. Is the enzyme that facilitates DNA synthesis
Mitosis: A. Occurs in cells that give to gametes B. produces haploid cells from diploid cells C. Produces daughter cells that are exact genetic copies of the parent cell D. Consists of two separate divisions, mitosis I and mitosis II
C. Produces daughter cells that are exact genetic
Describe three ways that cancer cells differ from normal cells.
Cancer cells divide when they should not, invade surrounding tissues, and move to other locations in the body.
Why do cells divide?
Cells divide in order to make more cells. This can allow an organism to grow. Each of us begins life as a single fertilized egg cell that underwent millions of rounds of cell division to produce all the cells that comprise the tissues and organs of our bodies. Cells also divide in order to heal wounds. As this cut heals, new cells will replace those damaged by the injury.
Classification
Classified by the type of cell that the tumor cell resembles Carcinoma Sarcoma Lymphoma and leukemia Germ Cell Blastoma
A cell that beings mitosis with 46 chromosomes produces daughter cells with: A. 13 Chromosomes B. 23 Chromosomes C. 26 Chromosomes D. 46 Chromosomes
D. 46 Chromosomes
When a trait is highly heritable: A. It is influenced by genes B. It is not influenced by the environment C. The variance of the trait in a population can be explained primarily by variance in genotypes D. A and C are correct E. A, B, and C are correct
D. A and C are correct
After telophase I of meiosis, each daughter cell is: A. Diploid, and the chromosomes are composed of one double-stranded DNA molecule B. Diploid, and the chromosomes are composed of two sister chromatids C. Haploid, and the chromosomes are composed of one double-stranded DNA molecule D. Haploid, and the chromosomes are composed of two sister chromatids
D. Haploid, and the chromosomes are composed of two sister chromatids
At metaphase of mitosis: A. The chromosomes are condensed and found at the poles B. The chromosomes are composed of one sister chromatid C. Cytokinesis beings D. The chromosomes are composed of two sister chromatids and are lined up along the equator of the cell
D. The chromosomes are composed of two sister chromatids and are lined up along the equator of the cell
DNA in cell division
DNA condenses during cell division: DNA in its replicated but uncondensed form prior to cell division. During cell division, each copy of DNA is wrapped neatly around many small proteins, forming the condensed structure of a chromosome. After DNA replication, two identical sister chromatids are produced and joined to each other at the centromere.
DNA Replication
DNA replication results in the production of two identical daughter DNA molecules form one parent molecule. Each daughter DNA molecule contains half of the parental DNA and half of the newly synthesized DNA. The DNA polymerase enzyme moves along the unwound helix, tying together adjacent nucleotides on the newly forming daughter DNA strand. Free nucleotides have three phosphate groups, two of which are cleaved to provide energy for this reaction before the nucleotide is added to the growing chain.
The cell cycle
During interphase, the DNA is copied. Separation of the DNA into two daughter nuclei occurs during mitosis. Cytokinesis is the division of the cytoplasm, creating two daughter cells. During interphase, there are two stages when the cell grows in preparation for cell division, G1 and G2 stages, and one stage where the DNA replicates, the S stage. The chromosomes are separated and two daughter cells are formed during the M phase.
A quantitative trait: A. May be one that is strongly influenced by the environment B. Varies continuously in a population C. May be influenced by many genes D. Has more than a few values in a population E. All of the above
E. All of the above
Gametes
Each egg and sperm is unique: Because each sperm is produced independently, the set of chromosomes in each sperm nucleus will be a unique combination of the chromosomes that the man inherited from his mom and dad.
Environmental effects
Example: Body weight in mice has a strong genetic component In a population where weight is variable, bigger mice have bigger offspring, smaller mice have smaller offspring What happens if we vary the environment?
Gregor Mendel
Father of modern genetics Experiments with pea plants Established many of the rules of heredity Laws of Mendelian inheritance
Meiosis
Form of cell division that produces specialized cells called gametes Gametes contain half the number of chromosomes of the parent cell
A homologous pair of chromosomes
Homologous pairs of chromosomes have the same genes but may have different alleles. The dominant allele is represented by an uppercase letter, while the recessive allele is shown with the same letter in lowercase. Note that the chromosomes of a homologous pair each have the same size, shape, and positioning of the centromere.
Crossing over
If a flower with the above arrangement of alleles undergoes meiosis, it can produce two different types of gametes for these two genes if crossing over does not occur or four different types of gametes for these two genes if crossing over occurs at L
Random alignment
In this example, the organism undergoing meiosis has only hour chromosomes. The organism inherited the blue chromosomes from its father and the red chromosomes from its mother. When there are two homologous pairs of chromosomes, two possible alignment A and B can occur. These different alignments can lead to novel combinations of genes in the gametes.
Interphase and meiosis
Interphase consists of G1, 2, and G2 and is followed by two rounds of nuclear division, meiosis I, and meiosis II
Cell Cycle and Mitosis
Mitosis - portion of the cell cycle in which DNA is apportioned into two daughter cells Somatic cells - any cell type that does not produce sex cells Cells that divide by mitosis - 3 steps 1) Interphase 2) Mitosis 3) Cytokinesis
List the ways in which mitosis and meiosis differ
Mitosis occurs in somatic cells, meiosis in the cells that give rise to gametes. Mitosis produces daughter cells that are genetically identical to parent cells with novel combinations of chromosomes and half as many chromosomes as compared to parent cells.
Twins
Monozygotic (identical) twins form from one fertilization even and thus are genetically identical. Dizygotic (fraternal) twins form from two independent fertilizations, resulting in two embryos who are only as genetically similar as any other siblings.
Cellular Respiration
Much of this process of cellular respiration takes place within the mitochondrion. The breakdown of glucose by cellular respiration requires oxygen and ADP plus phosphate. The energy stored in the bonds of glucose is harvested to produce ATP (from ADP and P), releasing carbon dioxide and water.
Most common in different genders
Over 100 types of cancers affect humans Most common in males Lung cancer Prostate cancer Colorectal cancer Stomach cancer Most common in females Breast cancer Colorectal cancer Lung cancer Cervical cancer
In what ways is the cell cycle similar in plant and animal cells, and in what ways does it differ?
Plant and animal cells both have interphases followed by M phases. Cytokinesis differs in plant and animal cells
Define the terms proto-oncogene and oncogene.
Proto-oncogenes are genes that control the cell cycle. Oncogenes are mutated versions of proto-oncogenes
A dihybrid cross
Punnett squares can be used to predict the outcome of a cross involving two different genes. This cross involves two pea plants that are both heterozygous for the seed-color and seed-shape genes.
Quantitative traits
Quantitative traits - traits that have many possible values not just an on or off character Continuous variation - a range of slightly different values for a trait in a population -Polygenic traits - influenced by more than one gene -Transcription regulators - proteins that determine if and when a gene is expressed -In Continuous variation - each genotype capable of producing a range of phenotypes depending on outside influences -Most traits that show continuous variation influenced by both genes and the environment
List two things that happen during meiosis that cause gametes to differ from one another.
Random alignment of homologues and crossing over
What property of cancer cells do chemotherapeutic agents attempt to exploit?
Rapid cell division
Causes of cancer
Roughly 90-95% of cancer cases are due to environmental factors Environmental - any cause that is not inherited genetically Tobacco (25-30%) Diet and obesity (30-35%) Infections (15-20%) - viruses are the usual infectious agents Radiation (up to 10%) - ionizing and non-ionizing radiation Stress Lack of physical activity Environmental pollutants - physical agents (e.g., asbestos) Carcinogen - substance that causes cancer or increases the rate of its development
Environmental effects
The environment can have powerful effects on highly heritable traits. If genetically similar populations of mice are raised in radically diverse environments, then differences between the populations are entirely due to environment.
Mutants
The formation of different alleles: Different alleles for a gene may form as a result of copying errors. In this analogy, misspellings (mutations) do not change the meaning of the word (allele), but some may result in altered meanings (different allele function) or have no meaning at all (no allele function)
Karyotype
The pairs of chromosomes in this karyotype are arranged in order of decreasing size and numbered from 1 to 22. The X and Y sex chromosomes are the 23rd pair.
Hereditary
The remaining ~3-10% are due to inherited genetics Less than 0.3% of the population carry a genetic mutation that has a large risk for cancer Examples; Mutations in genes BRCA1 and BRCA2 With a >75% risk of breast cancer and ovarian cancer Hereditary nonpolyposis colorectal cancer (HNPCC) ~3% of people with colorectal cancer
Genetics
The study of genes, genetic variation and heredity in living organisms
Genotype
all genetic characteristics that determine the structure and functioning of an organism; also a single gene locus to distinguish one allele or a combination of alleles, from another
Lymphoma and leukemia
arise from blood-forming cells
Germ Cell Tumor
arise from pluripotent (stem) cells
Sarcoma
arising from connective tissue
Heterozygous
containing two forms (alleles) of a gene, one derived from each parent
Homozygous
containing two identical alleles at a gene locus
Carcinoma
derived from epithelial cells
Blastoma
derived from immature cells or embryonic tissue
Recessive
gene whose expression is masked by an alternative allele in a diploid, heterozygous state
Phenotype
physical expression of the interaction between the genotype and the environment; outward appearance and behavior of organism
Mitosis
portion of the cell cycle in which DNA is apportioned into two daughter cells
Benign
stay in one place and do not affect surrounding structures Some of these benign tumors remain harmless, others become cancerous
Pleiotropy
the ability of one gene to affect many different functions -Very few genes are limited in their effect to a single trait
