Topics 10 And 3 Review

Front 1

Evolution does not occur when:

Back 1

1. There is a large population
2. There is random mating
3. There is no mutation
4. There is no natural selection
5. There is no gene flow

Front 2

Define polyploidy

Back 2

Polyploidy is when an organism (usually plants because of their ability to self–pollinate) have more than one full set of chromosomes. This is usually due to an error in meiosis where the cell does not go under cytokinesis.

Front 3

Define disruptive selection

Back 3

Disruptive selection is when individuals are more fit when they have one of either extreme traits. Natural selection favours both extreme traits over the average

Front 4

Define directional selection

Back 4

Directional selection is when an individual that has the extreme form of a particular trait is more fit. Natural selection favours one extreme trait over other phenotypes

Front 5

Define stabilizing selection

Back 5

Stabilizing selection is when individuals with the average trait are more fit. Natural selection favours those with an average form of the trait.

Front 6

What do the variables in the Hardy Weingburg equations represent?

Back 6

q = the recessive allele/gene frequency
p = the dominant allele/gene frequency

p + q = 1

p^2 = homozygous dominant genotype/phenotype/trait frequency

q^2 = homozygous recessive genotype/phenotype/trait frequency

2pq = heterozygous genotype/phenotype/trait frequency

p^2+2pq+q^2=1

Front 7

What is an example of polyploidy?

Back 7

An example is the onion (A. cepa), 16 Chromosomes. The English Leek (A. cepa) has 32 chromosomes. Because the leek can no longer breed with the onion, speciation is said to have occurred.

Front 8

What is phyletic gradualism?

Back 8

Phyletic gradualism, or just gradualism, is the continuous change at a constant rate of heritable traits over a long period of time.

Front 9

How does gradualism arise?

Back 9

Through the gradual accumulation of mutations/variations over time.

Front 10

What gives evidence to gradualism?

Back 10

Gradual change in the fossil record with intermediate forms between species.

Front 11

Give an example of gradualism

Back 11

The modern horse evolved slowly with a gradual change of size and structure of foot with changing habitat.

Front 12

What is punctuated equilibrium?

Back 12

Evolution proceeding rapidly, in short bursts, cushioned by long periods of stability (no little to no change)

Front 13

What happens during periods of stability in punctuated equilibrium?

Back 13

Organisms become well suited to the environment, natural selection acting to maintain characteristics.

Front 14

Equilibrium is punctuated by:

Back 14

rapid environmental change (e.g. volcanic eruption, meteor impact) which leads to directional selection.

Front 15

What evidence is there for punctuated equilibrium?

Back 15

Gaps in the fossil record and lack of intermediate forms for many species.


Strata in fossil record show the appearance of many new species after a mass extinction.

Front 16

Define adaptive radiation

Back 16

Adaptive radiation is the rapid speciation of a single ancestral lineage into two or more similar but distinct species. This occurs when different populations of the same species are exposed to a variety of different environmental selection pressures. Each population must adapt to a different niche, therefore making morphological adaptions as well. This may be further enhanced by reproductive isolation.

Front 17

What is a similarity between convergent and divergent evolution?

Back 17

Both explain the presence of similar structures in different organisms.

Front 18

Describe Convergent evolution

Back 18

Different ancestor. Converge to produce analogous structures. Species appearance becomes more similar over time. Species are unrelated (genetically different). E.g. Wings in insects, birds and bats.

Front 19

Describe Divergent evolution

Back 19

Common ancestor. Diverge to produce homologous structures. Species appearance becomes more different over time. Species are closely related (share genetic homology). E.g. Pentadactyl limb structure (vertebrates).

Front 20

What are the four forms of reproductive isolation?

Back 20

Temporal, Ecological, Behavioral, and Geographic

Front 21

Define temporal reproductive isolation

Back 21

When organisms cannot mate because of different mating seasons.

Front 22

Define ecological reproductive isolation

Back 22

Although in the same area, the two species cannot mate because they live in different habitats.

Front 23

Define behavioral reproductive isolation

Back 23

When two species cannot mate because they do not exhibit the right mating rituals (song, dance, etc.) or produce the right pheromones for each other. Members of the species will only mate with and be attracted to those who exhibit the correct behaviors.

Front 24

Define geographic reproductive isolation

Back 24

What was once a continuous population is divided into two or more smaller population by geographical circumstance, preventing them from mating with each other. (e.g. rivers change course, continents drift, organisms migrate, unfavorable habitat between the two populations)

Front 25

Define gene pool

Back 25

The total collection of different alleles in an interbreeding population.

Front 26

Define allele frequency

Back 26

Allele frequency is the proportion of all copies of a gene that is made up of a particular gene variant (allele).

Front 27

What is a gene?

Back 27

A heritable factor that consists of a length of DNA that controls or influences a specific characteristic.

Front 28

Where are genes found?

Back 28

Genes are found on a particular position on a chromsome (called a locus or loci)

Front 29

What is an allele?

Back 29

Alleles are the various forms of a gene (or alternate forms). They differ from each other by one or only a few nitrogenous bases.

Front 30

Does the number of genes determine an organism's complexity?

Back 30

No. An organism's complexity should also be determined by its organ systems, complexity of nervous system, and stimulus in response.

e.g. Humans have 22 333 genes while grapes have 30 434 genes.

Front 31

How do new alleles arise?

Back 31

By mutations.

Front 32

What is a mutation?

Back 32

Random, rare changes in genetic material. They are permanent changes in the nitrogen base sequences of DNA.

Front 33

Are mutations good or bad for an organism?

Back 33

Mutations can be positive (increases fitness), negative (decreases fitness or leads to mortality), or neutral/silent (no effect).

Front 34

What is a base substitution mutation?

Back 34

A mutation resulting in the change of a single nitrogenous base.

Front 35

What could be a possible effect of a base substitution mutation?

Back 35

Changing one base could mean that a different amino acid is placed on the polypeptide chain. This could have a major influence, no influence, or tiny influence on the physical characteristics of the organism or protein function. E.g. Sickle cell anemia

Front 36

What are the causes of sickle cell anemia? What are the affects of the disease?

Back 36

Base substitution mutations. By changing the sixth codon triplet GAG to GTG, valine is produced instead of glutamic acid. The haemoglobin becomes sickle.

The biggest effect is interrupted is that sickle cells block blood flow and carry less oxygen.

Front 37

How is sickle cell anemia an example of natural selection.

Back 37

Those with sickle cell anemia are immune to malaria, so in countries where malaria is a large cause of death, the debilitating disease can actually give individuals an advantage in their environment. Over time, sickle cell anemia becomes more prominent because they passed on their genes. Natural selection favored them.

Front 38

Define genome

Back 38

The genome is the whole of the genetic information (genetic material) of an organism. Think of it like a library. This includes genes and non-coding sequences.

Front 39

What is the Human Genome Project?

Back 39

The Human Genome Project was a mission whose primary goals were to discover the complete set of human genes and make them accessible for biological study. AKA, to determine the complete sequence of DNA bases in the human genome.

Front 40

Did the Human Genome Project succeed?

Back 40

Yes, but they now have the goal of discovering the function of all genes as well.

Front 41

Draw a prokaryotic cell

Back 41

Front 42

How is prokaryotic DNA unique in comparison to eukaryotic DNA?

Back 42

-Single chromosome

-Plasmids

-One copy of each gene

-Copies are made before binary fission (asexual reproduction)

Front 43

What is unique about plasmids?

Back 43

-No histones

-small circular rings of DNA

-not responsible for normal life processes

-used for survival characteristics

-can be passed between prokaryotes

-can be incorporated into the nucleoid chromsome

-Can be used to transfer genes into bacteria

Front 44

What are the characteristics of eukaryotic DNA?

Back 44

-linear DNA held in helix

-associated with histones

-two copies of each gene (one maternal, one paternal)

-DNA strands are supercoiled into chromosomes when not being transcribed

Front 45

Chromosomes vary by:

(4 things)

Back 45

-Length

-position of centromere

-banding pattern

-what genes are on it (in the same species the same gene is always located at the same loci)

Front 46

What are homologous chromosomes?

Back 46

Homologous chromosomes carry the same sequence of genes but not the necessarily the same alleles of those genes. One is from mom, one is from dad.2n --> full chromosome set.

Front 47

What is a diploid nucleus?

Back 47

Diploid nucleus has two of each chromosome (2n). All human genes (except for the gametes) are diploid, and they have 46 chromosomes.

Front 48

What is a haploid nucleus?

Back 48

Haploid nucleus has one of each chromosome (n). Only gametes are haploid. Human haploid cells have 23 chromosomes.

Front 49

Define sister chromatids

Back 49

When chromosomes replicate up prior to cell division, the two identical chromosomes are said to be sister chromatids until they split at the centromere at the start of anaphase.

Front 50

What is a characteristic feature of a member of a species?

Back 50

A characteristic feature is the chromosome number. All members of a species have the same number of chromosomes, and only organisms with the same amount can interbreed. To a degree, n number (chromosome number) reflects the complexity of the organism.

Front 51

How do chromosome numbers change?

Back 51

It is possible for chromosomes to fuse or split during evolution, but chromosome numbers tend to stay the same for millions of years.

Front 52

What is the difference between a karyotype and a karyogram?

Back 52

Karyotype: the humber and type of chromosomes in a nucleus, not a photo or diagram of them.

Karyogram: a diagram/photo of chromosomes present in a nucleus of a eukaryote cell arranged in homologous pairs of decreasing length.

Front 53

How are chromosomes arranged in a karyogram?

Back 53

By size, shape, centromere location, and banding pattern.

Front 54

How is sex determined?

Back 54

Everyone has two sex chromosomes, but women always have XX and men always have XY. The presence and expression of the SRY gene on the Y chromosome leads to male development.

Front 55

What is the difference between autosomal chromosomes and sex chromosomes.

Back 55

22 pairs of autosomes, which are in homologous pairs.

1 pair of sex chromosomes, which are either XX or XY. There are many genes in the non-homologous region which are not present in Y.

Front 56

What was John Cairns known for?

Back 56

Producing images of DNA molecules from E. coli. He was able to measure the length of the molecule through autoradiography.

Front 57

What is genome size?

Back 57

The total number of DNA base pairs in one copy of a haploid genome. (for humans it is 3.2 billion base pairs).

Front 58

How can one identify Down Syndrome and sex from a karyogram?

Back 58

Through a karyogram, if there are three 21 chromosomes (trisomy 21), the human has down syndrome. If there are two X chromosomes, the human is female, and if it has an X and a Y it is male.

Front 59

What are some differences between mitosis and meiosis? (give 3)

Back 59

-mitosis vs meiosis

-one division vs two divisions

-diploid cells produced vs haploid gametes produced

-no crossing over vs crossing over in prophase I

-No chiasmata vs chiasmata form

-homolous pairs do not associate vs homologous pairs associate as bivalents

-diploid to diploid vs diploid to haploid

Front 60

Define meiosis

Back 60

Meiosis is a reduction division of the nucleus to form haploid gametes.

Front 61

What are three reasons why there is near infinite variation in genetic information of gametes?

Back 61

Random orientation and crossing-over, as well as sexual reproduction, a fusion of two gametes.

Front 62

What is independent assortment?

Back 62

The idea that the separation of alleles for one gene will occur independently of the separation of alleles for another gene. This does not apply to linked genes.

Front 63

How is random orientation related to independent assortment?

Back 63

Random orientation something that happens during metaphase I in prophase. Homologous pairs line up randomly on the equator, and then are separated from each other during anaphase I. This promotes independent assortment.

Front 64

Why is meiosis important in sexual reproduction.

Back 64

To preserve the number of chromosomes, a reduction division must go under way. As gametes fuse in sexual reproduction, there must n chromosomes to form 2n in the zygote.

Front 65

What occurs during Interphase I of meiosis?

Back 65

-DNA replication

-chromosome duplicates attached by a centromere form sister chromatids

-preparation for meiosis

Front 66

What occurs during Prophase I of meiosis?

Back 66

-synapsis causes homologous pairs to form a bivalent

-nuclear membrane dissolves

-centrioles migrate to the poles of the cell

-crossing-over between non-sister chromatids may occur.

Front 67

What is crossing over? What are chiasmata?

Back 67

Crossing over is the exchange of genetic material between homologous chromatids. Chiasmata form between non-sister chromatids, which is the point around which the exchange of alleles may occur.

Front 68

Is crossing over sure to happen?

Back 68

No. Crossing over might, and often does, happen, but it does not always happen.

Front 69

What are the three steps to crossing over?

Back 69

1. Synapsis. Homologous chromosomes associate.

2. Chiasmata formation.

3. Recombination. Segments of DNA twist around, swapping segments of DNA.

Front 70

What is the standard notation for writing genotypes of linked genes?

Back 70

Front 71

What are the key points when drawing chiasmata?

Back 71

• Use colour of shading toindicate the each of the sister chromatids

• Rememberthe homologous chromosomes are in synapsis – before and after crossing over the chromosomesshould be shown close together.

Front 72

What occurs during metaphase I of meiosis?

Back 72

-Random orientation

-bivalents line up on the equator

-spindle fibres attach to the centromeres of the sister chromatids.

Front 73

Difference between random orientation and independent assortment?

Back 73

Random orientation: Behaviour of homologous pairs or pairs of sister chromatids in meiosis.

Independent assortment: behavour of alleles of unlinked genes as a result of meiosis.

Front 74

What occurs in anaphase I of meiosis?

Back 74

-bivalent is split and half the chromosomes move towards each pole.

-spindle fibres contract or shorten.

-reduction division

Front 75

What occurs in telophase I of meiosis?

Back 75

-cytokinesis begins to occur

-new nuclei form

-chromosomes decondence

Front 76

What is non-disjunction? How many gametes does it affect?

Back 76

Non-disjunction is a cell's failure to perform meiosis correctly. Homologous chromosomes fail to separate correctly at anaphase. If it occurs during Anaphase I, it affects all gametes. If it occurs during anaphase II it affects half of the gametes.

Front 77

What is the effect of non-disjunction? Give an example.

Back 77

Trisomy (one chromosome too many), or monosomy (one chromosome too few. E.g. Trisomy 21 (AKA Down Syndrome) is when an individual has three of chromosome 21.

Front 78

What is amniocentisis?

Back 78

Amniocentesis is type of prenatal testing given to pregnant women to determine the karyotype of the child they are carrying. A sample of amniotic fluid is taken with a syringe. The fluid contains cells from the foetus, which is used for karyotyping.

Front 79

What is Chorionic Villus Sampling?

Back 79

A type of prenatal testing. A biopsy needle takes a few cells from the chorion (a membrane in the placenta), which are then cultured. When enough cells have grown, they are used for karyotyping.

Front 80

What are the risks of prenatal testing?

Back 80

There is a chance that a miscarriage might occur.

Front 81

What occurs in prophase II of meiosis?

Back 81

-nuclear membrane dissolves

-no crossing-over

-centrioles move to opposite poles

-chromosomes consisting of two sister chromatids.

Front 82

What occurs in metaphase II of meiosis?

Back 82

-pairs of sister chromatids align at the equator

-random orientation

-spindle fibres attach to centromeres.

Front 83

What occurs in anaphase II of meiosis?

Back 83

-Spindle fibres contract and shorten.

-The centromeres split

-the chromatids become chromosomes and are pulled to opposing poles.

Front 84

What occurs in telophase II of meiosis?

Back 84

-nuclear membrane reforms

-chromosomes decondense

-new haploid nuclei are formed

-cytokinesis begins

-four haploid gamete cells created

Front 85

Which phase of meiosis is this?

Back 85

Anaphase II

Front 86

Which phase of meiosis is this?

Back 86

Metaphase II

Front 87

Which plants did Mendel work with?

Back 87

Pea plants

Front 88

What are Mendel's laws? (3)

Back 88

1. Law of dominance

2. Law of segregation

3. Law of independent assortment

Front 89

Explain the law of dominance.

Back 89

If there is an organism with alternate forms of a gene, it will express the form that is dominant.

Front 90

Explain the law of segregation.

Back 90

When gametes fuse, each have one allele for every gene. A diploid cell therefore has two alleles for each trait.

Front 91

Explain the law of independent assortment.

Back 91

Each pair of alleles separates independently from other pairs of genes (as long as they are not on the same chromosome).

Front 92

Define genotype and phenotype.

Back 92

Genotype: reprentation of alleles through letters (AA, Aa, aa, Bb)

Phenotype: Characteristic/trait of an organism (blood type, hair colour, earwax type)

Front 93

Define dominant and recessive alleles.

Back 93

Dominant allele: allele that is expressed.

Recessive allele: allele that is only expressed when in the homozygous state.

Front 94

Define codominant alleles.

Back 94

Both alleles have an affect on phenotype when in heterozygote.

Front 95

What is a test cross procedure?

Back 95

A procedure used to find out the genotype of an organism by breeding it with an organism of known genotype. (Can be illustrated with a punett square)

Front 96

What is a monohybrid cross?

Back 96

A genetic cross which involves one trait and one pair of contrasting genes.

Front 97

Cross between a heterozygous smoothseed and a wrinkled seed pea plant.(Smooth is dominant over wrinkled)

Back 97

Choose a letter to represent thealleles in the cross. Write the genotypes of the parents andstate the gametes. Enter the gametes at the top and sideof the punnett square for F1 generation. Complete the punnett square by fillingin the offspring. Determine the phenotypic ratio. Determine the genotypic ratio. Determine probability of phenotype

Front 98

What is the notation for co-dominant punnet square?

Back 98

Capital C with superscript capital letters representing allele

Front 99

Roan coat color seen in some shorthorncattle which is a mixture of red hairs and white hairs. Each individual hair is either all red or allwhite, but both appear together.Cross a roan shorthorn bull with awhite shorthorn cow. Include P1, F1, GR and PR. Determine the probability of getting a redoffspring?

Back 99

Front 100

What is the notation for incomplete dominance (heterozygote is a blend of allele phenotype. E.g. red and white make pink)

Back 100

Capital letter with ' to signify different allele. E.g. red = RR

white = R'R'

Pink = RR'

Front 101

What is an example of multiple alleles?

Back 101

Blood types (The term multipleallele is used to describe a genethat has three or more alleles, and each allele can produce a distinct phenotype)

Front 102

What is the notation for blood types?

Back 102

Front 103

What is sex-linkage?

Back 103

Genes that are found on the sex chromosomes.

Front 104

3 examples of sex-linked disorders

Back 104

Colour blindness

Haemophilia

Muscular dystrophy

Front 105

Notation for sex-linked genes?

Back 105

sex linked alleles are designated byadding a superscript tothe letter X ONLY.A letter if the gene is known or a question mark if it is unknown.

Front 106

Are calico male cats possible? Why or why not?

Back 106

Not possible because it is a case of sex-linked co-dominance. Two X chromosomes are therefore required to make it happen. The only way a male can be calico is if it has three sex chromosomes, two X and one Y.

Front 107

Are genetic diseases common?

Back 107

No, especially since many genetic diseases are autosomal recessive. The chances of both parents carrying a mutant gene are slim.

Front 108

Cystic fibrosis is a __________ ___________ disorder.

Back 108

recessive autosomal

Front 109

Huntington's disease is a __________ ___________ disorder

Back 109

dominant autosomal

Front 110

What are the rules of pedigrees?

Back 110

-Males are squares, females are circles

-Males always on the left of marriages

-Generations represented by roman numerals on the left hand side

-Children are below parents and are listed and numbered in chronological order of birth

-a genotype is listed below each circle or square

-shaded circle/square shows an exhibited phenotype.

-half shaded or dotted circles are carriers

Front 111

Awoman and man who both have normal vision have two children. Their oldest son has normal vision, but theiryoungest son is colorblind. The youngestson marries a normal vision woman and they have two color-blind daughters. Red-greencolor-blindness is a recessive sex-linked disorder.

Back 111

note that generation one genotypes should be below and men should be on the left.

Front 112

How do you analyse a pedigree? Autosomal vs. Sex linked

Back 112

Front 113

How do you analyse a pedigree? Dominant vs. Recessive

Back 113

Front 114

Back 114

1. autosomal dominant

2. sex linked dominant

3. sex-linked recessive

4. recessive autosomal

Front 115

What is a dihybrid cross

Back 115

Unlike a monohybrid cross, a dihybrid cross determines the allele combinations of offspring for two particular genes that are unlinked.

Front 116

How do you find the gametes of the parents in a dihybrid cross?

Back 116

Using the FOIL method. E.g. For parent AaBb, gametes would be:

-First (AaBb = AB) -Outside(AaBb = Ab) -Inside (AaBb = aB) -Last (AaBb =ab)

Front 117

When crossing two heterozygous parents in a dihybrid cross, what will be the genotypic and phenotypic ratio patterns?

Back 117

GR pattern: 1 : 2 : 2 : 1 : 4 : 1 : 2 : 2 : 1

PR pattern: 9 : 3 : 3 : 1

Front 118

How do you do a dihybrid cross?

Back 118

The same as a monohybrid cross, except you have to find the gametes of the parents, and the punnet square may be up to 16 squares.

Front 119

Define linked genes.

Back 119

Linked genes are genes which do not assort independently of one another because their gene loci are on the same chromosome. The only way they can be separated is through recombination (via crossing over).

Front 120

Define linkage group.

Back 120

A group of linked genes that are often inherited together because of their location on the same chromosome (e.g. red hair, pale skin, and freckles).

Front 121

For an individual with linked genes AABB and aabb, the gametes before recombinants are AB and ab. If recombination occured, what would the recombinants be?

Back 121

aB and Ab

Front 122

How can you identify linked genes?

Back 122

-Through a dihybrid cross, if most of the offspring resemble the parent's phenotypes, it is likely because the genes are linked.

- Heterozygous testcross of unlinked genes = 1 : 1 : 1 : 1 phenotypic ratio

-Heterozygous testcross of linked genes = 1 : 1 : 0.1 : 0.1 phenotypic ration (uncommonphenotypes are recombinants)

Front 123

What is polygenic inheritance?

Back 123

The inheritance of a single phenotypic trait that is controlled by two or more pairs of genes.

Front 124

Polygenic inheritance gives rise to _________ __________ in the phenotype.

Back 124

continuous variation

Front 125

What are two examples of polygenic inheritance?

Back 125

Human skin colour, wheat kernal colour

Front 126

How does polygenic inheritance give rise to continuous variation?

Back 126

Multiple genes give a small, equal influence over the phenotype. In affect, the blend together, giving a gradation effect in phenotype.

Front 127

What is epistasis?

Back 127

Epistatic genes are genes that suppress the effect of a gene at another locus (in polygenic inheritance).

e.g. The gene for albinism is epistatic because even though someone might have the gene for pigmentation, the albino gene does not allow pigment expression to occur.

The epistatic gene can be dominant or recessive.

Front 128

Coat color in dogs. Gene 1 controls coat colour. Blackcoat color (B) is dominant to brown (b)Gene 2 controls pigment expression.This is an epistatic gene that prevents pigment formation and color formation (W) in the dominant form to thegene that does not prevent pigment formation and color formation (w) in the recessiveform.Cross a white dog (heterozygous for nopigment, and heterozygous for black colour) and a black dog (heterozygous forblack colour expression.)

Back 128

Front 129

What is discontinuous variation?

Back 129

Individuals fall into descrete classes or categories that cannot be measured across a range. E.g. blood groups. There is no in between option. You either are in a blood group or you aren't.

Front 130

What is continuous variation?

Back 130

Individuals fall into a complete range of measurements from one extreme to the other. E.g. Height has a complete range of phenotypes, from very short to very tall and everywhere in between.

Front 131

How else might polygenic traits be influenced other than genetics?

Back 131

Environment. E.g. Dietary factors and childhood diseases can effect height. Exposure to sun, burns, and scarring can effect skin colour.

Front 132

In brief, why do women tend to have lighter skin tones than men living in the same population?

Back 132

Lighter skin allows for greater intake of vitamin D from the sun, which is necessary for embryo development. The more vitamin D a mother intakes, the healthier a newborn is likely to be as vitamin D is necessary for calcium absorption.

Front 133

What methods are involved in the analysis of DNA and gene transfer?

Back 133

-copying DNA in a lab -- the polymerase chain reaction (PCR)

-Using DNA to reveal its owner's identity -- DNA profiling

-Mapping DNA by finding where every A,T, C, and G -- gene sequencing, including the Human Genome Project

-Cutting and pasting genes to make new organisms -- gene transfer

-Clone cells and animals

Front 134

At a crime scene, a small amount of blood is found, carrying a small amount of the criminal's DNA. What method might a forensic investigator use so that more DNA can be used for the investigation?

Back 134

PCR (polymerase chain reaction) may be used. It amplifies small samples of DNA through the use of a machine called a thermocylcler.

Front 135

What are the three steps to PCR?

Back 135

1. Denaturation: DNA is heated to separate two strands

2. Annealing: DNA primers attach to opposite ends of the target sequence

3. Elongation: A heat-tolerant DNA polymerase (Taq) copies the strand

Front 136

Multiple suspects have been identified for a crime. How method might forsenic investigators use to identify the culprit?

Back 136

DNA profiling using gel electrophoresis.

Front 137

Most human's genes are almost exactly alike. Then how can biologists determine between individuals using gel electrophoresis?

Back 137

Satellite DNA, sections of DNA separating coding genes, are made up of short tandem repeats and vary in length between different individuals. These fragments are what is used for DNA profiling.

Front 138

How does electrophoresis separate DNA fragments?

Back 138

DNA is put into wells in porous agarose gel.

The gel is exposed to an electric current.

Because DNA is negatively charged, it will go towards the positive end. Heavy, long fragments of DNA stay close to the wells because they cannot move easily through the gel. Light, short fragments travel farther because they move easily through the porous gel.

Front 139

How is DNA profiling used for paternity testing?

Back 139

DNA samples from the mother, child, and potential father are used. If the child matches with half of dad's bands and half of mom's band's, it is a match.

Front 140

What is a standard lane in gel electrophoresis?

Back 140

A standard lane is the "control" lane. It has a band at every possible spot.

Front 141

Another word for gene transfer is_____________.

Back 141

transgenics

Front 142

Why is transgenics possible?

Back 142

The genetic code is universal (with a few rare exceptions).

Front 143

What is a basic technique used for gene transfer involving plasmids, a host cell, restriction enzymes, and DNA ligase.

Back 143

Foreign DNA has the gene of interest cut with restriction enzymes, making a sticky end pattern (along with plasmid).

PCR

DNA ligase is used to ligate the gene of interest and plasmid.

Creates recombinant DNA. Insert into bacterium.

Bacteria will clone itself and recombinant DNA

DNA purification.

E.g. The cloning of genetically engineered bacteria to create human insulin.

Front 144

What is the difference between transfection and transformation?

Back 144

Transfection is when recombinant plasmid is inserted into the host cell (for eukaryotic cells) and transformation is when recombinant plasmid is inserted into the desired host cell (for prokaryotic cells)

Front 145

What are some uses for transgenic crops?

Back 145

1. Engineering crops to extend shelf life of fresh produce (Flavr Savr tomatoes).

2. Engineering crops to provide protection from insects (Bt corn made to be toxic to corn borers)

3. Other (Salt tolerant tomato plants, golden rice made with beta-carotene.

Front 146

What are some uses for transgenic animals?

Back 146

1. Engineering animals to enhance production (Sheep made to produce more wool (cysteine))

2. Engineering animals to produce desired products (sheep engineered to produce alpha-1-antitrypsin to help those with emphysema)

3. Other (goat milk containing spider silk. human insulin produced by bacteria)

Front 147

What are the potential benefits to transgenic crops?

Back 147

-Allows new characteristic into the gene pool

-Increased productivity of food.

-Less use of pesticides, reducing cost of farming

-Can grow in new regions, decreasing deforestation.

Front 148

What are the potential harms to transgenic crops?

Back 148

-Could have surprise harmful effects on humans.

-Accidental mixing with native plants may result in competition.

-Possibility of cross pollination into weeds, making super weeds

-Reduces genetic variation/biodiversity (killing corn borers)

Front 149

What is a clone?

Back 149

A clone is a group of genetically identical organisms, derived from a single original parent cell.

Front 150

Are there natural methods of cloning?

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Yes. Many plant species and some animal species clone themselves. E.g. Runners are clones produced by asexual reproduction by many plants, allowing fast propagation.

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Which animals clone themselves?

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Star fish, Plenaria, Mammals (twins)

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How can animal cells be cloned at an early embryonic stage?

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Micropipetting is used to extract stem cells and grow them elsewhere, making identical twins.

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How can adult animals be cloned?

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Through Somatic Cell Nuclear Transfer (SCNT).

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What are the steps of Somatic Cell Nuclear Transfer?

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-A surrogate mother is treated with hormones to increase egg production (such as FSH)

-An egg cell is enucleated, removing the surrogate mother's genetic information.

-The egg cell is fused with the nucleus of a body cell of another animal (the one to be cloned), making the egg cell diploid.

-An electric shock stimulates mitosis.

-After a blastocyst has formed, it is implanted into the surrogate mother's uterine lining.

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What is an example of an animal clone?

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Dolly the Sheep.

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Is human cloning possible?

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Yes, but it is illegal.

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What is the difference between reproductive cloning and therapeutic cloning?

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Reproductive cloning is done for the goal of making a living clone of an organism.

Therapeutic cloning is done for the goal of cloning an organism's tissues and using them for therapeutic uses (stem cells).

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What are the arguments for therapeutic cloning?

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-May be used to cure serious diseases.

-Stem cell research may result in future discoveries and beneficial technologies.

-Stem cells can be harvested from embryos which would have died anyway.

-Cells are taken at a stage when the embryo's nervous system feels no pain.

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What are the arguments against therapeutic cloning?

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-Involves the creation and destruction of human embryos.

-Embryonic stem cells could become cancerous cells if they continue to divide.

-More embryos are generally produced than needed, killing many excess embryos.

-Different technology could be developed to fulfill similar roles.