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biol1203 > UNIT 11 - HUMAN GENETICS > Flashcards

UNIT 11 - HUMAN GENETICS Flashcards

1
Q

Hereditary

A

Transmission of traits from one generation to the next

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2
Q

Genetics

A

Scientific study of heredity and hereditary variation

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3
Q

Gene (6)

A
  • Unit of hereditary that controls particular character
  • Sequence of DNA
  • Specific location on a chromosome
  • Determines particular character
  • Controls cellular structure/activities
  • Determines chemical structure of structural proteins of cell & enzymes
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4
Q

Allele

A

Specific form of gene which controls trait (eg. Specific allele for a hair color gene determines that an individual will have trait brown hair)

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5
Q

Character

A

Observable feature such as hair color and eye color

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6
Q

Trait

A

Variant of a character such as red hair or brown hair

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7
Q

Phenotype

A

An organism’s physical appearance

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8
Q

Genotype

A

An organism’s genetic makeup

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9
Q

Chromatin

A

Complex of DNA and protein that form chromosomes

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10
Q

Chromatid

A

Duplicated strands of DNA joined at the centromere during cell division

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11
Q

Chromosome

A

Large condensed and organized structures formed by tightly coiled chromatids

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12
Q

Diploid cell

A

2 sets of chromosomes found in all body cells except gametes

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13
Q

Haploid cell

A

1 set of chromosomes found only in gametes (sperm and egg)

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14
Q

Somatic cell

A

Cells in the body other than sperm and egg cells and contain 46 chromosomes (23 pairs) where each pair is from maternal and paternal sources

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15
Q

Autosomes

A

Any non-sex chromosome; 22 pairs

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16
Q

Sex chromosomes

A

1 pair of sex chromosomes

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17
Q

Female sex chromosome

A

XX

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18
Q

Male sex chromosomes

A

XY

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19
Q

Homologous

A

Means same information

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20
Q

Mitosis

A

Process by which one cell gives rise to 2 daughter cells

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21
Q

Why must cells divide by mitosis (2)

A
  • Growth: From fertilized egg to multi celled organism
  • Repair & renewal: Replace cells that die from normal wear and tear or injury
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22
Q

Cell cycle (5)

A
  • Interphase (non-dividing): Cell growth, DNA replication, organelle replication
  • Mitotic phases (prophase, prometaphase, metaphase, anaphase, telophase): Duplicated chromosomes separate
  • Cytokinesis: Division of cytoplasm
  • Two daughter cells produced
  • Identical to parent cell
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23
Q

Interphase:

A

Cell prepares for division

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24
Q

Prophase

A

Condensation of chromatin into visible chromosomes

25
Q

Metaphase

A

Alignment of chromosomes at the cell’s equator

26
Q

Anaphase

A

Separation of sister chromatids towards opposite poles

27
Q

Telophase

A

Nuclear envelope forms and chromatin relaxes

28
Q

Cytokinesis

A

Cytoplasm divides and two genetically identical daughter cells form

29
Q

Meiosis

A

Reproductive cell division that occurs in gonads and produce cells (gametes) with a haploid number of chromosomes and fertilization restores the diploid number of cells

30
Q

Major differences between mitosis and meiosis

A

Mitosis occurs in somatic cells, two daughter cells formed, number of chromosomes remains diploid in daughter cells, necessary for growth and repair, and crossing over does not take place. Meiosis occurs in gametic cells, four daughter cells formed, number of chromosomes become haploid in daughter cells, meiosis is necessary for sexual reproduction and crossing over takes place

31
Q

Nondisjunction

A

Refers to the failure of paired chromosomes to separate normally resulting in abnormal distribution of chromosomes in daughter cells

32
Q

Crossover and genetic recombination (3):

A
  • Homologous chromosomes synapse during prophase of meiosis I. Each chromosome consists of two sister chromatids
  • One chromatid segment exchanges positions with a homologous chromatid segment and crosses over (chiasma)
  • Each haploid gamete has one of the four chromosomes, two of the chromosomes are recombinant (new combination of genes)
33
Q

Dominant alleles

A

Masks the expression of another allele; do not skip generations and not hidden

34
Q

Recessive alleles

A

Presence is masked by dominant alleles; may be present but not expressed, can skip generations, expressed when both alleles recessive, MUST have 2 recessive alleles for trait to show

35
Q

Dominant and recessive alleles symbols

A

Dominant gene upper case, recessive gene lower case

36
Q

Homozygous

A

Same alleles on homologous chromosomes

37
Q

Homozygous dominant

A

RR

38
Q

Homozygous recessive

A

rr

39
Q

Heterozygous

A

Different alleles on homologous chromosomes (Rr)

40
Q

Autosomal inheritance

A

Involves characteristics coded by genes on autosomes (1-22 AKA non sex chromosomes)

41
Q

ABO gene

A

Located on chromosome 9, everyone has two copies of chromosome 9 so you have two ABO genes (from mom and dad)

42
Q

Mutation (5)

A
  • Sudden change in cell’s genetic material
  • Permanent alteration
  • Can be inherited
  • Spontaneous/induced (chemicals, irradiations)
  • Affect single gene and affect number of chromosomes at once
43
Q

How would a gene mutation be expressed in offspring

A

The mutation would have to be dominant, or would have to be present in a cell with a recessive allele inherited from other parent

44
Q

Wildtype allele

A

Used to describe the most common allele of any particular gene and used in situations where they may be an interest in comparing a rare mutant allele with the normal or wild type

45
Q

Albinism

A

Characterized by lack of pigmentation (melanin) in skin, hair and eyes caused by inability of melanocytes to manufacture tyrosinase which converts tyrosine to melanin

46
Q

Downsides of albinism (3)

A
  • Visual problems
  • Possible blindness due to light damage of retina
  • Sensitivity to UV radiation from sunlight
47
Q

Dominant disorders:

A

Usually lethal and much rarer than recessive disorders (eg. Polydactylism, Huntington’s disease, achondroplasia)

48
Q

Huntington’s disease

A

Gradual degeneration of nervous tissue and mental function, symptoms appear after 40

49
Q

Aneuploidy

A

Cell from which one or more chromosome has been added or deleted

50
Q

Monosomic:

A

Missing a chromosome (2n-1)

51
Q

Trisomic

A

Has an extra chromosome (2n+1)

52
Q

Down syndrome:

A

Aneuploidy either during gametogenesis or during early embryonic development and occurs in 1 in 900 births, most prevalent in older mothers (eg. 47, XX, +21; trisomy 21)

53
Q

Down syndrome features (8)

A
  • Mental retardation
  • Short head
  • Short neck
  • Short torso
  • Heart defects
  • Poor skeletal development
  • Slanted eyes
  • Enlarged tongue
54
Q

Turners syndrome

A

Result of aneuploidy in sex chromosomes, missing 1 X chromosome (45, X0)

55
Q

Turners syndrome features (4)

A
  • Lack of breast development and other secondary sex characteristics
  • Small in body size
  • Growth retardation
  • Webbing of neck
56
Q

Klinefelter syndrome

A

Sex chromosome aneuploidy, extra X chromosome in male (47, XXY)

57
Q

Klinefelter syndrome features (6)

A
  • Poorly developed secondary sex characteristics
  • Sterility (no sperm)
  • Small testes
  • Breast development
  • Increased height, long limbs
  • Decreased mental abilities
58
Q

Sex linked inheritance

A

Gene located on either sex chromosomes, generally refers to genes on X chromosome

59
Q

Colorblindness

A

Sex linked condition where females may be carriers and males are typically affected

biol1203 (12 decks)

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