biology: introduction to genetics Flashcards

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1
Q

WHAT IS GENETICS?

A

Understanding how characteristics are transmitted from parents to offspring
Began with Gregor Mendel
-1800s monk
- Researched pea plant heredity using observations and statistics
– Discoveries made apply to all organisms

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2
Q

what is heredity?

A

Passing of traits from parents to offspring

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3
Q

what did mendel do?

A

Studied seven traits of peas

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4
Q

trait

A

genetically determined variant of characteristic

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5
Q

how did mendel study his plants?

A

pollination experiments

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6
Q

pollination

A

Pollen from anther () transferred to ovary ()

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7
Q

self-pollination

A

Pollen and ovary from same plant

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8
Q

cross-fertilization

A

Pollen and ovary from different plants

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9
Q

true-breeding plants

A

All self-fertilized offspring have same trait as parent

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10
Q

what were Mendel’s conclusions?

A
  1. Pair of alleles controls each trait
  2. Law of Segregation
  3. Law of Independent Assortment
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11
Q

allele

A

different forms of a gene

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12
Q

gene

A

segment on DNA on chromosome that controls trait

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13
Q

dominant allele

A

hides the recessive trait

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14
Q

recessive allele

A

no observable effect on organism if dominant allele is present

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15
Q

law of segregation

A

Paired alleles segregate during meiosis

• Gametes receive one allele from each pair

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16
Q

law of independent assortment

A
  • Alleles sort independently during meiosis

* Genes for one trait do not influence inheritance of genes for another trait

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17
Q

Molecular genetics

A

Study of structure/function of genes & chromosomes

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18
Q

are all of mendels discoveries still true?

A

supported by current molecular genetics
each gamete has 1 allele for a gene
each somatic cell has 2 alleles for each gene

19
Q

dominant allele

A

capitol letters

20
Q

recessive alleles

A

lower case letters

21
Q

phenotype

A

Organism’s traits that are expressed

22
Q

genotype

A

Organisms genetic makeup; consists of alleles

23
Q

homozygous

A

When both alleles are alike
Ex. PP = homozygous dominant (purple flowers)
pp = homozygous recessive (white flowers)

24
Q

heterozygous

A
When both alleles are different
Ex. Pp = heterozygous
Since purple (P) is dominant, plant is purple
25
Q

can predictions be made about genetics of offspring?

A

yes using probability

26
Q

probability

A

Likelihood that a specific event will occur

27
Q

punnet square

A

Diagram used to predict genetics of offspring

28
Q

Monohybrid cross

A

only one trait is tracked

29
Q

testcross

A

Individual of unknown genotype is crossed with homozygous recessive
• Based on probability, can determine unknown genotype
Ex. Purple (P?) crossed with white (pp)
If no white offspring, what is genotype?
probably PP
If white offspring,
must be Pp

30
Q

dihybrid cross

A

Two traits are tracked instead of one.

31
Q

what are non-mendelian genetics?

A

genetics that do not follow mendel’s laws

  1. incomplete dominance
  2. multiple alleles
  3. codominace
  4. polygenic traits
  5. sex-linked inheritence
32
Q

incomplete dominance

A
Heterozygote phenotype is combination of parental phenotypes
red snapdragon (CRCR) x white snapdragon (CWCW) 
100% offspring are pink(CRCW)
33
Q

multiple alleles

A

A gene with two or more alleles

Ex. Blood type A, B, AB, or O

34
Q

codominance

A

Both inherited alleles are completely expressed

Ex. Roan coat in cattle

35
Q

polygenic traits

A

Traits produced by many genes

Ex. Skin color

36
Q

sex-linked inheritence

A

based on sex chromosomes

37
Q

sex chromosomes

A

Responsible for determining sex

XX – females; XY - males

38
Q

Y-linked genes

A

On the Y chromosome
Very few genes
Mainly code for testes and sperm development; testosterone

39
Q

X-linked genes

A

On the X chromosome
Males-
Since only one X, get whatever is on X chromosome
Females-
Since two Xs, dominant and recessive come into play

40
Q

carrier

A

Heterozygous for recessive disorder

• Show no symptoms, but may pass recessive allele to offspring

41
Q

is it a problem to have 2 Xs in females?

A

no; in fetus cells randomly switch off one chromosome or the other

42
Q

are some genes inherited together? why?

A

yes! Linked genes
Genes that tend to be inherited together because they are
located close together on the same chromosome

43
Q

how do you tell how far apart genes are on chromosome?

A

Genes far apart on a chromosome are more likely to crossover.
Use crossover frequency to create a genetic map.

44
Q

what else impacts phenotype?

A
  1. Environmental conditions like pH
  2. Sunlight
  3. Temperature
  4. Diet