Genetics

Question 1

Examples of Chromosomal Abnormalities

Answer 1

• Alteration of chromosome number:
  
  • Polyploidy—complete sets of extra chromosomes
  • Aneuploid—chromosome number not 23—trisomy (trisomy 21 = Downs Syndrome)
    
    • nondisjunction is common cause- occurs during meiosis when there is failure to separate chromosomes ( meiosis I) or sister-chromatids (meiosis II)
• Alteration in Chromosome Structure:
  
  • Inversions
  • Deletions
  • Translocations

Question 2

Single-gene disorders

Answer 2

• caused by mutations in individual genes
• may be present on one or both alleles

Question 3

_____ follows mitosis, forming two daughter or progeny cells

Answer 3

Cytokinesis

Question 4

Which of the following statements is true about an individual who is a carrier for the cystic fibrosis (CF) gene?

• Homozygous; suffers from CF
• Homozygous; does not suffer from CF
• Heterozygous; suffers from CF
• Heterozygous; does not suffer from CF

Answer 4

Heterozygous; does not suffer from CF

If an individual is a carrier, they are heterozygous for the recessive trait (in this case, CF), but they do not display the trait (because the trait is recessive)

Question 5

Mendels pundentt square

Answer 5

dominant and recessive alleles; homozygous and heterozygous

¼ = A ½ = Aa ¼ = a

Question 6

Mendel’s first law

Answer 6

Mendel’s first law, the principle of segregation, states that the two members of a gene pair (alleles) segregate (separate) from each other in the formation of gametes; half of the gametes carry one allele, and the other half carry the other allele

Question 7

involves the division of the nuclear material of a cell

Answer 7

Mitosis

Question 8

When in cell cycle does DNA replication happen?

Answer 8

S phase of cell cycle maintains the genomic information using DNA polymerase

Question 9

chromosome number that is not 23

Answer 9

aneuploid

an example is trisomy, trisome 21 is downs syndrome, a common cause is nondisjunction

Question 10

two genes together might create a new phenotype

Answer 10

collaborative

Question 11

Contains the basic genetic information, and its expression as proteins determines the various functions of that cell

Answer 11

DNA structure base A, T, G, C + sugar and phosphate

Question 12

Meiosis I

Answer 12

• Homologous chromosomes line up in the middle of the cell.
• Homologous chromosomes separate to opposite sides of the cell.
• Random shuffling of maternal and paternal chromosomes occurs.
• Crossing over or exchange between homologous segments of the sister-chromatids that make up each homologous chromosome occurs.
• Random shuffling and crossing over result in genetic recombination that ensures that genetic information in the offspring is unique.
• Result is two cells that contain 23 individual chromosomes. Each of these chromosomes has two copies or is composed of sister-chromatids.

Question 13

Genetic exchange of maternal and paternal information occurs during _____ through recombination

Answer 13

Meiosis

Question 14

many genes can affect one trait

Answer 14

polygenic

Question 15

What is semi-conservative replication?

Answer 15

when replicating each DNA molecule contains one original strand and one newly synthesized strand, it ensures that any mistakes or mutations introduced during the DNA replication process can be fixed

Question 16

The diploid nautre of somatic cells is maintained by _____ while the haploid number in the gametes is obtained through a process called _____

Answer 16

Mitosis, Meiosis

Question 17

Meiosis II

Answer 17

The result of meiosis I is two cells that each contain individual chromosomes that have been copied (sister-chromatids). There is no duplication of genetic material in between meiosis I and II. Meiosis II will involve the further separation of each of those sister-chromatids to generate four cells each with one copy of each of the 23 homologous chromosomes. Thus, from the original diploid parent cell there are now four haploid cells that contain one copy of each chromosome. Meiosis is the process that produces the gametes—sperm and ovum—that will fuse during fertilization to form the zygote

Question 18

Identifies mutations associated with disease, identifies markers of disease or predictors of disease risk or likelihodd of response to certain drug treatments

Answer 18

Human Genome Project

Question 19

one gene might depend on another

Answer 19

complementary

Question 20

If an unaffected mother carries one normal and one mutant allele on her X chromosome, what are the chances that she will transmit the defective gene to her sons?

• 25%
• 50%
• 75%
• 100%

Answer 20

50%

Because a son receives the X sex chromosome from his mother (who has one normal and one mutant allele), there is a 50% chance that the mutant allele will be inherited.

Question 21

The members of each pair of autosomes are also called _____

Answer 21

Homologues their sequences are very similar they have different “alleles” or copies of each of the genes

Question 22

Multifactorial Inheritance disorders

Answer 22

• Caused by a combination of variations in a number of genes that together produce or predispose an individual to a serious defect
• often in concert with environmental factors

Question 23

One of the chromosomes pairs consists of _______

Answer 23

sex chromosomes X and Y in males X and X in females the remaining chromosomes are called autosomes

Question 24

Single Locus genetic disorder, autosomal dominant traits

Answer 24

• Marfan syndrome (connective tissue defects)
• Achondroplasia (dwarfism)

Question 25

Single Locus Genetic disorder, Mitochondrial

Answer 25

* Affects energy metabolism * presents with multiple copies * Is inherited from the mother only

Question 26

Involves the reduction divisions that take the chromosomal content of germline cells from diploid (23 pairs of chromosomes) to haploid (23 individual chromosomes)

Answer 26

Meiosis

Question 27

Explain the several phases of mitosis

Answer 27

PMAT * Prophase where the nuclear membrane dissolves and two copies of each chromosome (sister chromatids) attach at the centromere. * Metaphase where the chromosomes are highly condensed and line up on the equatorial plane of the cell. * Anaphase where the sister chromatids separate and the chromosomes are pulled apart. * Telophase where the nuclear membrane forms around the two sets of chromosomes.

Question 28

**observable properties (traits) due to interaction between genotype and environment**

Answer 28

Phenotype

Question 29

**Examples of Sex Chromosome disorders**

Answer 29

* **Turner Syndrome** * **absence of all or part of the X chromosome** * **lack of development of ovaries/sexual characteristics** * **Klinefelter syndrome** * **one or more additional X chromosome with a normal male composition (XY**)

Question 30

Which type of chromosome alteration generally results in normal offspring? Deletion Inversion Translocation Ring formation

Answer 30

Translocation Translocation is the only chromosomal alteration where no genetic material is actually lost (chromosome parts are exchanged), so the offspring are usually normal. Offspring are translocation carriers, so their children may or may not be normal.

Question 31

There are two cell divisions that occur during meiosis

Answer 31

Meiosis I involves the reduction division stage that results in the formation of two haploid cells per diploid cell. Homologous chromosomes separate, but sister-chromatids (copies) remain together. Meiosis II which involves an equatorial division where sister chromatids are separated.

Question 32

How is the use of complementary base pairing arranged

Answer 32

Anti-parallel orientation Double-helix

Question 33

What is chromatin made of?

Answer 33

DNA and protein (histones)

Question 34

**Mutation that introduces a stop to protein synthesis**

Answer 34

Nonsense Mutations

Question 35

**Genetic Makeup**

Answer 35

Genotype

Question 36

genetic change in one of the cells of the body and cannot be transferred to the offspring or inherited

Answer 36

somatic mutation

Question 37

both, multiple genes and the environment could affect one trait

Answer 37

multifactoral

Question 38

**Mendels second law**

Answer 38

**the principle of independent assortment, states that genes for different traits assort independently of one another in gamete production.**

Question 39

Single locus genetic disorder, autosomal recessive traits

Answer 39

* Autosomal Recessive Traits * cystic fibrosis * Sickle Cell Anemia

Question 40

**Chromosomal disorders**

Answer 40

* caused by an excess or deficiency of genes contained within a whole chromosome or chromosomal segment

Question 41

disease process associated with translocation of chromosomes 9 and 22 of the Philadelphia chromosome

Answer 41

chronic myeloid leukemia (CML)

Question 42

Errors in the DNA sequence are called _____ which may involve changes to a single nucleotide or larger regions of DNA

Answer 42

mutations

Question 43

a genetic change found in the gametes, thus can be transmitted to offspring or inherited

Answer 43

germline mutation

Question 44

\_\_\_\_\_ in the genetic code means that not all mutations cause amino acid changes

Answer 44

* Redundancy Mutations that do not change the amino acid are called “silent”. * Mutations that alter the amino acid are termed “missense” and may or may not alter protein structure and thus function. * Other mutations may introduce a stop to protein synthesis and are called “nonsense”. * Mutations may involve the addition (insertion) or removal (deletion) of nucleotides in the DNA sequence.

Question 45

How many sets of chromosomes

Answer 45

23 pairs (autosomes and 1 set of sex chromosomes)

Question 46

Single locus genetic disorder, sex linked- X-linked recessive

Answer 46

* Duchene Muscular Dystrophy * Hemophilia A

Question 47

**Alteration of the DNA sequence (mutation) can give rise to \_\_\_\_**

Answer 47

disease

Question 48

Mutations can result in an aberrent protein sequence and improper protein structure can affect \_\_\_\_\_

Answer 48

function

Question 49

complete sets of extra chromosomes

Answer 49

polyploidy

Question 50

\_\_\_ are diploid, having two copies of each chromosome, while gametes are haploid, having only one copy of each chromosome

Answer 50

Somatic cells contains 23 pairs of chromosomes within the nucleus of that cell