Unit 1 - Genes and Genetic Diseases Flashcards

1
Q

consists of genetic material called nucleotides, to sequence determines which proteins are found in the cell.

A

genetic master code

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2
Q

what is the term for the flow of genetic information from DNA to RNA to proteins?

A

central dogma

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3
Q

list the three major processes involved in the preservation and transmission of genetic information.

A
  1. Replication
  2. Transcription
  3. Translation
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4
Q

the copying of DNA to form an identical daughter molecule.

A

DNA replication

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5
Q

why does the parent strand of DNA determine the sequence of the new daughter strand in DNA replication?

A

replication is based on complementary base pairing
A:T
C:G

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6
Q

DNA sequence used as a template to produce a complementary strand of RNA (mRNA).

A

transcription

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7
Q

what is the complementary base pairing in transcription?

A

A:U
C:G

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8
Q

mRNA is decoded and converted into a protein in which process?

A

translation

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9
Q

all proteins are made up which macro molecule?

A

amino acids

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10
Q

transcription takes place in which organelle of the cell?

A

ribosome

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11
Q

offspring of an organism

A

Progeny

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12
Q

structures in the nucleus that contain DNA, each is made of genes

A

chromosome

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13
Q

the basic unit of heredity, located in a particular position on the chromosome

A

gene

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14
Q

position each gene occupies along a chromosome

A

locus

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15
Q

one of two alternative genes that contain specific inheritable characteristics and occupy corresponding positions on paired chromosomes

A

allele

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16
Q

I trait of an organism produced by identical or nearly identical alleles

A

homozygous

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17
Q

possessing different alleles at a given chromosomal location

A

heterozygotes

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18
Q

display of human chromosomes based on links and location of their centromere’s

A

karyotype

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19
Q

the basic combination of genes of an organism

A

genotype

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20
Q

the expression of the gene were individual trait-physical appearance

A

phenotype

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21
Q

an individual who has a gene for a disease that is phenotypically normal

A

carrier

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22
Q

traits for which one of a pair of alleles is necessary for expression

A

dominant trait

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23
Q

traits for which two alleles of a pair are necessary for expression

A

recessive trait

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24
Q

a schematic method of classifying genetic data

A

pedigree chart

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25
Q

the percentage of individuals with specific genotype who exhibit the expected phenotype

A

penetrance

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26
Q

the extent of variation in phenotype of a particular genotype

A

expressivity

27
Q

different expressions of a disease gene depending on which parent transmits the gene

A

genetic imprinting

28
Q

what are the two characteristics that lead to chromosomal disorders?

A
  1. Structure

2. Number

29
Q

known to be caused by mutations in a single gene

A

single - gene disorders

30
Q

result from small variations in genes combined with environmental factors

A

multifactorial disorders

31
Q

what are the two categories of cells?

A
  1. Somatic cells

2. Gametes

32
Q

a cell with an exact multiple of haploid number i.e. 2N, 3N

A

euploid

33
Q

chromosome complement that is abnormal in number that is not an exact number N

A

aneuploidy

34
Q

normal separation and migration of chromosomes during cell division

A

disjunction

35
Q

failure of proper separation and migration of chromosomes during cell division

A

nondisjunction

36
Q

what is a result of non-disjunction?

A

one daughter cell receives both homologous chromosomes and the other daughter cell receives none. Primary cause of aneuploidy

37
Q

repeated gene or gene sequences. Can be caused by a deleted sequence from one chromosome which may be incorporated into the homologous chromosome

A

duplication

38
Q

the linear arrangement of genes on a particular chromosome is broken and the order of that portion of the gene is reversed

A

inversion

39
Q

transfer of part of one chromosome to a nonhomologous chromosome. This occurs when two chromosomes break and segments are rejoined in an abnormal arrangement

A

translocation

40
Q

also known as trisomy 21

A

Down’s syndrome

41
Q

cause of trisomy 21

A

non-disjunction of chromosome 21 during mitosis

42
Q

how is down syndrome diagnosed after birth?

A

based on facial appearance which includes:

  • low nasal bridge
  • protruding tongue
  • low set ears
43
Q

disease characterized by absence of an X chromosome (45X)

A

Turner’s syndrome

44
Q

most common karyotype of Turner’s syndrome shows which phenotype?

A

female

45
Q

what are the characteristics of diagnosis upon birth?

A
  1. Redundant next skin

2. Peripheral lymphedema

46
Q

disease characterized by the presence of an extra X chromosome (47XXY)

A

Klinefelter syndrome

47
Q

most common karyotype of Klinefelter syndrome shows which phenotype?

A

male

48
Q

what are the phenotypic characteristics of Klinefelter syndrome?

A
  1. Long lower extremities
  2. Sparse body hair with female distribution
  3. Gynecomastia in 50% of male cases
49
Q

characteristics of single-gene disorders

A
  1. Inherited genes can be on one or both chromosomes
  2. Inheritance patterns are determined on whether the genie is on an auto some or a sex chromosome (X chromosome)
  3. Inheritance is determined on whether the gene is a dominant or recessive trait
50
Q

what are the four basic patterns of inheritance?

A
  1. Autosomal dominant
  2. Autosomal recessive
  3. X-linked dominant
  4. X-linked recessive
51
Q

autosomal dominant inheritance

A
  • abnormal allele is dominant and the normal allele is recessive
  • abnormal phenotype is expressed
52
Q

characteristics of autosomal dominant inheritance

A
  1. Affected person has affected parent
  2. Affected person meeting with an affected person have affected and unaffected offspring in equal proportion
  3. Male and female are equally affected
53
Q

autosomal recessive inheritance

A
  • abnormal allele is recessive

- trait must be homozygous to be expressed

54
Q

characteristics of autosomal recessive inheritance

A
  1. Dominant or normal allele masks recessive trait
  2. Heterozygous often phenotypically normal
    3 trades trait is only expressed when both alleles are homozygous
  3. Trait usually expressed in siblings not in parents
  4. Males and females equally affected
  5. Both parents of affected child carry the recessive allele
55
Q

traits that are expressed in the mail and transmitted from father to all daughters (may not be expressed in female, female is carrier and can pass traits offspring)

A

X-linked traits

56
Q

X-linked recessive disorders

A
  • recessive gene on X-chromosome of mail is not balanced by normal gene (trait acts as dominant trait)
  • meeting between affected male and carrier femalemay result in effective female
  • carrier female transmits recessive X-linked trait to 50% of sons and daughters
57
Q

principles of X-linked recessive inheritance

A
  1. Males are predominately affected
  2. Affected males transmit to all daughters and no sons.
  3. sons of female carriers have a 50% risk of being affected
  4. Daughters of female carriers have a 50% risk of being carriers
58
Q

Huntington’s disease

A

single gene disorder that affects the neurological system and exhibits progressive dementia and uncontrolled movements of the limbs. Symptoms generally do not manifest themselves until after the age of 40

59
Q

Type 1 neurofibromatosis

A

also known as von Recklinghausen disease. It is mapped to a defect in the long arm of chromosome 17. It’s expression varies from light brown spots to malignant neurofibromatosis, seizures, gliomas, hypertension and mental retardation

60
Q

cystic fibrosis

A

autosomal recessive disease mapped to the long arm of chromosome 7. Causes defect in the transport of chloride ions which leads to salt imbalance (see notes for digestive and respiratory symptoms)

61
Q

Duchenne muscular dystrophy

A

X-linked recessive disease predominantly expressed in males. Beats to progressive muscle degeneration. Can affect heart and respiratory muscles leading to cardiac and respiratory failure

62
Q

characteristics of multifactorial inheritance

A
  • trait results from several genes acting together (polygenic trait)
  • environmental factors influence polygenic expression
  • both genes and environment contribute to variation in traits
63
Q

list the examples of multifactorial disorders discussed in class

A
  1. Pyloric stenosis
  2. Cleft lip and palate
  3. Neural tube defects
  4. Clubfoot
  5. Congenital heart disease
  6. Hypertensive heart disease
  7. Diabetes myelitis