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Biology 101 with Molumby > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

What is heredity?

A

Inheritance or transmission of traits from parent to off spring.

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2
Q

What is genetics?

A

The study of how information is transmitted from one living organism to the next.

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3
Q

How is every living thing organized?

A

Via coded material called genetic material

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4
Q

What happens to genetic material during reproduction?

A

It is duplicated and transmitted to the next generation of living organism.

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5
Q

What is a gene?

A

It is a sequence of DNA that codes for a single genetic instruction. Typically the instruction is for the building of a protein, but the protein may also activate genes in a cell of neighboring cell.

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6
Q

Is every aspect of our species constructed based on code from DNA?

A

Yes, it is.

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7
Q

How is the information contained in DNA translated into living organism?

A

Via cytological machinery or cellular machinery. Two words for the same thing.

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8
Q

Are the impact of genes predictable?

A

No, genes are impacted by other gene and the environment.

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9
Q

What is an allele?

A

Different versions of the same gene. Moreover, we all have genes for eye color. But, one allele might code for blue, another for green and a another for brown.

For each gene, we typically get one allele from mom and another from Dad. As in I got two alleles for blue eyes.

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10
Q

What is an example of a small change in DNA code having a big impact?

A

In humans, if GAG is recoded GUG, sickle cell anemia results.

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11
Q

What are prokaryotes?

A

Simplest, oldest and most common organism on earth. Almost always single celled. They have much smaller genomes than eukaryotes.

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12
Q

What are the four principle blood types?

A

A, B, O and AB

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13
Q

What a pure-breeding or true-breeding line?

A

Consists of individuals that produce offspring identical to themselves when they are mated with themselves. Said another way, they are individuals of the same phenotype that when crossed always produce individuals of the same phenotype. Moreover, they are homozygous for the gene in question.

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14
Q

What is a hybrid?

A

A a offspring that is a cross between two homozygous parents. Hybrids are always heterozygous.

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15
Q

What is a reciprocal cross?

A

A cross in which the phenotype of the male and he female are reversed and compared with a prior cross. These types of crosses are intended to test the role of parental sex on inheritance patterns.

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16
Q

Prezygotic isolation mechanism

A

This type of isolation prevents mating. Leads to what is called allopatric speciation. Moreover, populations that geographically divided do not have the gene flow to stay a unitary species. And, by genetic drift, natural selection, and new mutations evolve into separate species.

Once the geographic barrier is removed the two incipient species might meld together by allele flow and again become one species. Or they might remain reproductively isolated.

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17
Q

Postzygotic isolation mechanism

A

Isolation leads to speciation. This type of isolation prevents fertilization after mating has occurred.

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18
Q

polyploidy

A

Organisms containing more than two sets of chromosomes.

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19
Q

Sympatric Speciation

A

When species whose geographic region overlap, evolve into new speciation. This is usually due to polyploidy and and non-random mating.

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20
Q

Cladogenesis

A

When a new species evolves from a parents species that continues to exist.

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21
Q

Phylogeny

A

family tree describing how species are related.

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22
Q

Systematics

A

The study of phylogeny

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23
Q

Taxonomy

A

The process of describing and naming organisms

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24
Q

What is the most widely accepted school of systematics?

A

Clasistics which infers phyogenic patterns based on homologies.

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25
What is a homologous characteristic?
A character state two species inherited from a common ancestor.
26
How are phylogenic trees constructed?
They are constructed based on homologous characteristics
27
What is homoplasy?
When a trait evolves in multiple places. Moreover, it is not homologous (ie evolving from the same ancestor). Moreover, two species have the same trait but no common ancestor.
28
Testcross
When a homozygous recessive individual is crossed with a individual with the dominant phenotype but an unknown genotype. This cross is typically used to determine the genotype of the parent with the dominant phenotype. That phenotype can either be heterozygous dominant or homozygous dominant.
29
What was Mendel's first step?
He crossed pure lines that differed in just one trait. In his first experiment it was whether the seeds were round or wrinkled.
30
What did Mendel find in the F1 of his first round wrinkled cross?
Every single pea in the F1 was round. This meant that round seeds were dominant. Proving that blending inheritance could not be the method of inheritance.
31
What is the ratio of the F2 generation for a single loci cross? Assuming the parent generation was a monohybrid cross?
3:1
32
What did Mendel do after his monohybrid cross of round and winkled seeds resulted in all rounds seeds?
He allowed the F1 to self-polinate
33
What causes Huntington's disease?
It is caused by a dominant gene.
34
Are dominant alleles automatically more common than recessive?
No, dominant alleles just refers to what wins in a given situation not to the overall frequency.
35
What other traits did Mendel test with early monohybrid crosses? What ratio did he consistently find in the F2 for the ration of the dominant trait to the recessive trait?
Seed shape, seed color, pod shape, pod color, flower color, flower and pod position, stem length. 3:1
36
What is the null hypothesis?
The commonly accepted point of view. In this class the null hypothesis will typically be independent assortment.
37
What is a gamete?
A mature haploid male or female germ cell that is able to unite with another of the opposite sex in sexual reproduction to form a zygote.
38
Do all allelic variation produce major differences?
No, Sometimes they produce no variation. Other times, a single nucleotide substitution can produce major changes. For example, sickle cell anemia is caused by changing one sequence GAG-->GUG.
39
What are prokaryotes?
Simplest, oldest most common organisms on the planet. Organisms in the domains of archaea and bacteria are both prokaryotes. Smaller genome than eukaryotes Single loop of DNA Do not have sexual reproduction, but they do have several forms of gene exchange. Rather they go through fission. Stretched out, its gene would 500 times longer than DNA itself. The DNA loop replicates itself before fission and than each daughter cell gets one loop of DNA. Most eukaryotes have several order of magnitude more DNA than prokaryotes
40
How many genes in a typical bacterium?
1200
41
In eukaryotes, does every cell have the same DNA?
Yes, though only a faction of the DNA in each cell is active. Some gene are permanently turned off during development
42
What are histones?
They are the structure around which DNA is wrapped. A second histone keeps the DNA in place. This entire structures is called nucleosomes.
43
What is the ratio of the F2 generation when the parent generation was pure bread? Another way to ask this question is the ask what is the phenotype ratio of a cross between two heterozygous individuals?
It is 3:1. The F1 generation of two pure breeding parents is always all dominant. The F2 generation is 3 dominant one recessive.
44
What is the principle of segregation?
It is how Mendel explained the reappearance of certain traits in the F2 generation. If there were two characteristics each gene pair must segregate that is separate into distinct gametes during the formation of eggs or sperm. As a result each gamete contains one allele for each gene.
45
How many copies of each gene does each gamete have?
1
46
What is the genotype ratio of a monohybrid cross?
1/4 will be homozygous dominant. 1/2 will be heterozygous. 1/4 will be homozygous recessive.
47
What is the ratio in a dihybrid cross when the parents are heterozygous for both traits?
9:3:3:1
48
What is a test cross?
When an individual with only recessive alleles is crossed with an individual with an unknown genotype, in order to determine the genotype of that individual.
49
What will the ratio be of a dihybrid cross of an individual that is heterozygous and an individual that is recessive for both traits?
There will be a quarter of each possible genotype present. 1:1:1:1
50
In a dihybrid cross, what will be the ratio if a homozygous dominant is crossed with a homozygous recessive?
Only the dominant phenotype will be present.
51
What are Mendel's laws?
1. ) The Principle of segregation | 2. ) The principle of independent assortment
52
What accounts for Mendel's laws?
In around 1902, two scientists (Sutton and Boveri) realized that segregation and independent assortment could be explained by meiosis. This is called the chromosome theory of inheritance. It explains why traits located on different chromosomes are independently assorted. It also explains Mendel's principle of segregation.
53
What are the standard distributions in the first, second and third standard deviations?
68%, 95% and 99.7%
54
What is the 68, 95 and 99.7 rule.
The amount of data that lies within one, two and three standard deviations of the mean.
55
What does wild type mean?
The most common phenotype in the wild is called wild-type
56
Who was Thomas Hunt Morgan? And what was the significance of his work?
The person who began studying Drosophila melanogaster. His work led him to the discovery of sex chromosomes.
57
How did hunt Morgan discover sex chromosomes?
He noticed that wild-type flies had red eyes, but when he found a mutant male with white eyes he crossed it with wild-type red eyed females. The F1 of this cross was entirely red eyed. (White eyed males; red eyed female--> all offspring red eyed). Then Hunt Morgan took a white eyed female and crossed her with a red -eyed male. This time all the females int eh F1 had red eyes but the males all had white eyes. (Red eyed male; white eyed females-->red eyed female off spring; white eyed male off spring) Morgan had discovered x-linked traits and x and y chromosomes.
58
What is the hypothesis of x-linked traits?
Females have two copies of genes that are x-linked because they have two copes of the x-chomorosome. Whereas males only have one copies of genes that are on the x chromosome.
59
What is linkage?
The tendency of particular alleles of different genes to be inherited together. Linkage is seen when gene are on the same chromosome.
60
In fruit flies, what in addition to eye color is x-linked and commonly studied?
Body color.
61
What is wild type for eye and body color as it was studied by Thomas Hunt Morgan?
Red eyes and gray body.
62
For fruit flies studied by Morgan, what was the mutant eye and body color?
white and yellow.
63
Do linked traits violate the rule of independent assortment?
Yes
64
What does recombinant mean?
When novel combination are created.
65
Are linked gene inherited together?
Yes, except when crossing over occurs.
66
What does polymorphic mean?
When more than two distinct phenotypes are present because of multiple allelism, the trait is considered polymorphic.
67
What is crossing over?
Always happens during meiosis. It accounts for genetic variation because it when genetic material is swapped.
68
What are homologous chromosomes?
An individual's pair of chromosomes one from your mother, one from your father.
69
What are the three sources of genetic variation?
1. ) Independent assortment of chromosomes--> During meiosis homologous pairs separate randomly. For each chromosome, you have a 50% chance of getting either chromosome your parent got from his or her parents. Given that the number of possible combinations of chromosome in each gamete is 2^23 or about 8 million. 2. ) Cross-over. During meiosis the chromosomes that are about to be divided and becomes haploid recombine via cross-over in all sorts of ways. For each chromosome there is typically two or three points of crossover. 3. ) Random fertilization--> Due to independent assortment, there are 8 million possible chromosome combinations for each gamete. Therefore there are 8 million x 8 million possible combinations.
70
What causes Marfan's
A mutation at the FBN1 allele. It is dominant
71
What is an example of how environment affects genes?
Phenylketonuria is an autosomal recessive allele that causes retardation, but if the diet is changed people are unaffected
72
Describe the inherit can pattern of Cystic Fibrosis
autosomal recessive
73
Describe the inherit can pattern of Tay Shachs
autosomal recessive
74
Describe the inherit can pattern of Huntington's
autosomal dominant
75
Describe the inherit can pattern of Hemophilia
sex linked recessive
76
Describe the inherit can pattern of color blindness
sex linked recessive
77
Describe the inherit can pattern of duchesses
sex-linked recessive
78
Describe the inherit can pattern of sickle cell
autosomal recessive
79
Describe the inheritance pattern of down syndrome?
It is a chromosomal disorder cause by trisomy 21. The individual has 47 chromosomes
80
Turner's syndrome
small statured female. Missing their second gender chromosome. Individuals are XO. They have 45 chromosomes
81
Klinefelter's Syndrome
People XXY. They are male with small genitals and are sterile.
82
What is non-disjunction?
It causes either monosomy or trisomy.
83
What is recombination?
It is the result of crossing over.
84
What is lissencephaly?
A rare autosomal recessive gene on chromosome 7. Leads to profound developmental delays.
85
What is ectrodactly?
Dominant autosomal. Severly deformed digits.
86
What makes an individual rh positive or negative?
Rh factor is coded at 2 loci, RhD and RhCE. If people have the dominant allele at either loci, they are Rh+. If people have the recessive allele at both loci, they are Rh-
87
What is the significance of the Yarrow?
They are an example of how environment and gene determine character. Mountain plants have selected for a variety of alleles that help them deal with the winter. When they are grown in a friendlier climate they grow taller but not as tall as plants adapted of the warmest climate.
88
What is the law of segregation?
It when the "particles" (i.e. genes) segregate. Moreover, individuals produce gametes with only one particle. Said another way, the particles (or factors contributing to the trait) segregate.
89
What is the law of independent assortment?
These particles (traits or genes) assort independently of one another
90
What heterostyly?
When individuals can only mate with their opposite phenotype.
91
What are bird sex chromosomes?
ZW and ZZ ZW female ZZ male
92
What is Penetrance?
The probability that you will express your genotype.

Biology 101 with Molumby (6 decks)

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