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Science - Living Earth > Ch11+14 - Genetics > Flashcards

Ch11+14 - Genetics Flashcards

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Biology 101 flashcards
1
Q

What is genetics?

A

the study of heredity

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2
Q

What is a gene?

A

A segment of DNA that controls traits

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3
Q

What is an allele?

A

A version of a gene

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4
Q

Who was Gregor Mendel? What was he known for?

A
  • Father of Genetics (1822)
  • Austrian monk who worked at a monastery garden
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5
Q

What are the parts and functions of a basic flower?

A
  • Sepal: bottom of flower, protects flower bud
  • Petals: attract pollinators whole protecting inner reproductive structures
  • Stamen: Male parts of flower, produces pollen
  • Carpel: Female parts of flower, produces eggs
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6
Q

Why did Gregor Mendel choose garden peas to perform his research?

A
  • Garden peas self pollinate - Sexual structures are enclosed with petals
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7
Q

Define pollination

A

Transferring pollen from anthers to stigma of flowers for fertilization

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8
Q

What is true-breeding? Example

A

Seeds produced will inherit the same qualities as parents due to self-pollination
- Ex. True-bred tall plants will only produce tall plants

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9
Q

How did Gregor Mendel prevent self pollination?

A

He cut away the stamen

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10
Q

What is cross pollination? How did Mendel cross-pollinate?

A

Cross-pollination: Pollen from 1 flower fertilizes egg of another flower
- Mendel dusted flower 1 with pollen from flower 2

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11
Q

When/how is a test cross used?

A

Crossing dominant phenotype with a pure organism to find its genotype

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12
Q

Monohybrid vs Dihybrid cross? Ratios?

A

Monohybrid: involving 1 trait (3:1)
Dihybrid: involving 2 traits (9:3:3:1)

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13
Q

What is a trait?

A

A specific characteristic determined by genes and varies in individuals

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14
Q

What are hybrids?

A

the offsprings of a cross involving parents with different traits

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15
Q

What is the principle of dominance?

A

Some alleles are dominant while others are recessive

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16
Q

What is the law of segregation?

A

A gene has 2 alleles which are equally separated during gamete formation

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17
Q

Define probability

A

the likelihood that an event will occur

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18
Q

When is a punnett square used?

A

Diagram that shows the offspring gene combinations from a genetic cross

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19
Q

Homozygous vs. Heterozygous

A

Homozygous: having 2 identical alleles
Heterozygous: having 2 different alleles

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20
Q

Phenotype vs Genotype

A

Phenotype: physical characteristics
Genotype: genetic makeup

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21
Q

What is the principle of independent assortment?

A

genes for different traits segregate independently of each other during gamete formation

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22
Q

What are the principles beyond Mendelian genetics?

A
  1. Some alleles are neither dominant nor recessive
  2. Many traits are controlled by multiple alleles/ genes
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23
Q

What is complete dominance?

A

When the dominant allele is always expressed

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24
Q

What is incomplete dominance? Example

A

One allele is not completely dominant over another
The heterozygous phenotype is a blend of both parents
Ex. homozygous red x homozygous white = heterozygous pink
- No recessive allele = shown using 2 different capital letters

25
Q

What is codominance?

A

Both alleles contribute to the phenotype
Ex. AB Blood type is codominant

26
Q

What happens with multiple alleles? Ex

A

Having more than 2 alleles
- Ex. 3 blood types

27
Q

Define polygenic traits. Examples

A

Having traits controlled by 2+ genes
Ex. height, skin color

28
Q

What is a karyotype?

A

A visual of fully condensed, paired up chromosomes
- used to analyze chromosomes

29
Q

Define pedigree. When is it used?

A

Chart which shows the relationship within a family
- Used to study how a trait is passed from 1 generation to the next
- Infer genotypes of family members

30
Q

Expand on the Rh Blood group

A

Determined by a single gene w/ 2 alleles
- Positive (dominant): you have the antigen
- Negative (recessive): you don’t have the antigen

31
Q

Expand on the ABO blood group

A

Consists of 3 alleles
IA & IB are codominant –> AB
i is recessive –> O

32
Q

List the recessive allele disorders

A

Albinism
Cystic Fibrosis
Galactosemia
Phenylketonuria (PKU)
Tay-Sachs Disease

33
Q

What are the effects of albinism?

A

Lack of pigment in skin, hair and eyes

34
Q

What are the causes and effects of cystic fibrosis?

A

Causes:
- Recessive allele in chromosome 7
- Deletion of 3 bases in the middle of a sequence
- The protein allows chloride ions to pass across biological membranes
- Deletion causes improper protein folding - cells do not transport protein to cell membrane

Effects
- Tissue starts malfunctioning
- Excess mucus in lungs, digestive tract, liver
- Increased susceptibility to infections
- Death in infancy, unless treated

35
Q

What are the effects of galactosemia?

A
  • Inability to digest galactose
  • accumulation of galactose in tissues
  • Mental retardation
  • Eye and liver damage
36
Q

What are the causes and effects of phenylketonuria?

A

Causes
- Recessive allele in chromosome 12
- Lack enzyme needed to break down phenylalanine (amino acid in milk)

Effects
- Accumulation of phenylalanine in blood/ tissue
- Abnormal skin pigment
- Mental retardation

37
Q

What are the effects of Tay-Sachs disease?

A
  • Nervous system breaks down
  • Lipid accumulation in brain cells
  • Mental deficiency
  • Blindness
  • Death in childhood
38
Q

List the dominant allele disorders?

A

Achondroplasia
Huntingtons disease
Hypercholesterolemia

39
Q

What are the effects of achondroplasia?

A

Dwarfism

40
Q

What are the causes and effects of Huntington’s disease?

A

Causes
- Dominant allele at end of chromosome 4
- Inheriting a single dominant allele

Effects
- mental deterioration
- Uncontrollable movements

41
Q

What are the effects of Hypercholesterolemia?

A
  • Excess cholesterol in blood
  • Heart disease
42
Q

List the codominant allele disorders?

A

Sickle cell disease

43
Q

What are the causes and effects of sickle cell disease?

A

Causes
- Allele codes for betaglobin –> insert of valine instead of glutamine results in hemoglobin sticking together
- Forms sickle shape
- Bent/ twist red blood cells get stuck in capillaries, blood stops moving
- Heterozygous sickle cell allele allows resistance to malaria

Effects
- Sickled red blood cells
- Physical weakness
- Damage to many tissues

44
Q

Define genome

A

Complete set of genetic information

45
Q

How many chromosomes do humans have?

A

22 pairs of autosomes
1 pair of allosomes (X + Y)

46
Q

Which chromosome determines sex?

A

Y chromosome

47
Q

Where are sex-linked genes located?

A

Most are located on X chromosome
- Y chromosome is smaller & contains few genes

48
Q

List the sex-linked disorders

A

Color blindness
Hemophilia
Duchenne Muscular Dystrophy

49
Q

What are the causes of color blindness?

A

X chromosome contains 3 genes associated with color vision
- 2 recessive alleles causes color blindness

50
Q

What are the causes of hemophilia?

A

Recessive allele in which a protein necessary for normal blood clotting is missing

51
Q

What are the causes and effects of Duchenne Muscular Dystrophy?

A

Causes
- Defective version of certain gene coding for muscle protein

Effects
- Weakening & loss of skeletal muscle
- Rarely live past adulthood

52
Q

Define hemizygous

A

Males are hemizygous since they only have 1 copy of most sex-linked genes

53
Q

How do females function with 2 X chromosomes when only 1 is needed for basic living? Example of effects

A

In females, 1 X chromosome is switched off & formed into dense region in the nucleus (Barr body)
- Ex. Color of coat spots is located on X chromosome
- One X chromosome has alleles for brown/black spots, if 1 X chromosome is switched off, fur will have both brown & black spots on various places

54
Q

Define nondisjunction

A

Failure of separation of homologous chromosomes/ sister chromatid

55
Q

List the autosomal chromosome nondisjunction disorders & their basic effects

A

Down syndrome: Trisomy 21
- Mental retardation
- Increased susceptibility to diseases

Edwards syndrome: Trisomy 18
- Increase in infant mortality
- Development delay

Patau syndrome: Trisomy 13
- Small head
- Heart, vision, hearing problems
- Weak muscle tone
- Brain disorders

56
Q

List the sex chromosomal nondisjunction disorders & their basic effects

A

Turner syndrome: XO
- Sex organs do not develop at puberty

Metafemale: XXX
- Taller than normal
- Slender torso

Klinesfelter syndrome: XXY
- High pitch voice
- No facial hair
- Mental retardation

Jacobs syndrome: XYY
- Tall (super males)

57
Q

What is a mutation

A
  • Mistakes in gene duplication/ nondisjunction
  • Changes in nucleotide-base sequence of a gene or DNA molecule
58
Q

List the types of chromosomal mutations

A

Deletion: loss of piece of chromosome
Inversion: segment of chromosome breaks/flipts/ reattaches to same chromosome
Translocation: segment breaks & reattaches to nonhomologous chromosome

Science - Living Earth (11 decks)

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