biology: introduction to genetics Flashcards

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
can predictions be made about genetics of offspring?
yes using probability
26
probability
Likelihood that a specific event will occur
27
punnet square
Diagram used to predict genetics of offspring
28
Monohybrid cross
only one trait is tracked
29
testcross
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
dihybrid cross
Two traits are tracked instead of one.
31
what are non-mendelian genetics?
genetics that do not follow mendel's laws 1. incomplete dominance 2. multiple alleles 3. codominace 4. polygenic traits 5. sex-linked inheritence
32
incomplete dominance
``` Heterozygote phenotype is combination of parental phenotypes red snapdragon (CRCR) x white snapdragon (CWCW)  100% offspring are pink(CRCW) ```
33
multiple alleles
A gene with two or more alleles | Ex. Blood type A, B, AB, or O
34
codominance
Both inherited alleles are completely expressed | Ex. Roan coat in cattle
35
polygenic traits
Traits produced by many genes | Ex. Skin color
36
sex-linked inheritence
based on sex chromosomes
37
sex chromosomes
Responsible for determining sex | XX – females; XY - males
38
Y-linked genes
On the Y chromosome Very few genes Mainly code for testes and sperm development; testosterone
39
X-linked genes
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
carrier
Heterozygous for recessive disorder | • Show no symptoms, but may pass recessive allele to offspring
41
is it a problem to have 2 Xs in females?
no; in fetus cells randomly switch off one chromosome or the other
42
are some genes inherited together? why?
yes! Linked genes Genes that tend to be inherited together because they are located close together on the same chromosome
43
how do you tell how far apart genes are on chromosome?
Genes far apart on a chromosome are more likely to crossover. Use crossover frequency to create a genetic map.
44
what else impacts phenotype?
1. Environmental conditions like pH 2. Sunlight 3. Temperature 4. Diet