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Biology 100 > Midterm 3 (Ch.13-15) > Flashcards

Midterm 3 (Ch.13-15) Flashcards

1
Q

Lecture 13

Inheritance and genetics

A

Todays Lecture, Still need to finish rest of ch. 13 and ch.12

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2
Q

Crossing Over and Linkage

A

Homologous chromosomes line up during meiosis
Parts of maternal and paternal chromosomes migrate

  • Linkage :
    - two genes on the same chromosome
    - Not independently assorted
    - Segregate together

Crossing-over causes them to separate
Crossing-over reduces genetic linkage

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3
Q

Impact of crossing-over

A 
Linked genes should always assort together
Should have resulted in two phenotypes
----both recessive or both dominant traits
----50% each
                    v
                    v
Crossing over changes that result
Result is less clear-cut
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4
Q

Autosomal recessive diseases

A

Represents several thousand disorders – mild or lethal
Usually both parents are carriers

Heterozygous (Aa)»>Don’t show the phenotype

Two carriers have a ¼ chance of producing affected offspring

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5
Q

Autosomal dominant diseases

A

One copy of the gene causes the disorder
More rare than recessive diseases

Affected individuals usually don’t survive to reproduce
Recur due to new mutations

Some diseases express late in life
More common; individuals can reproduce

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6
Q

Sex determination

A

During reproduction males determine sex
If the sperm has an X, it’s a girl
If the sperm has an Y, it’s a boy

Y has the SRY gene: Sex-determining Region of Y
Males have only one X

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7
Q

Genetic differences between individuals

A

Offspring are not genetic clones of parent
Variation is important for evolution

Variation is produced in four ways:

              - Mutations
              - Independent assortment
              - Crossing over
              - Fertilization
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8
Q

Meiosis and independent reassortment

A

Each homologous chromosome is independently assorted
23 pairs
2^23or 8,388,608 possible gametes
Fertilization: 2^23x 2^23 possible combinations
—over 64 trillion possible offspring

Gametes are sex cells

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9
Q

Genetic diseases

A

Pedigree analysis

Shows disease patterns in families

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10
Q

Crossing-over reduces genetic linkage

A

Homologous chromosomes line up during meiosis

Parts of maternal and paternal chromosomes migrate

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11
Q

Inherited chromosomal abnormalities

A

Some disorders are caused by mutated chromosomes
(not common, usually lethal)

Two main types:
changes in chromosome structure
a)Deletion
b)Inversion
c)Translocation
d)Duplication

changes in chromosome number— errors in meiosis

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12
Q

Inherited chromosomal abnormalities

A

errors in chromosome structure

errors in chromosome number
Most zygotes are not viable
Down syndrome-trisomy 21—–extra 21

Extra X and Y are possible
XXY males:
*Klinefelter syndrome
*Normal life span and intelligence
*Smaller testicle and reduced fertility
*Some with feminine characteristics

XXX females or XYY males
—–Mild changes

XXXY, XXXX or X0 females
—-Wider range of problems,
including mental retardation

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13
Q

Lecture 14

DNA Technology

A

DNA

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14
Q

DNA technology for the analysis and manipulation of DNA

A

Help understand biological processes
Aid in classification of organisms
Important for identification of critical genes
Increase production of important pharmaceuticals
Advanced alteration of crops through genetic modification
Analysis of individuals

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15
Q

Working with DNA

A
  • –DNA extraction
    - Open the cell membranes
    - Remove macromolecules
  • –Use enzymes from cells
    - Able to manipulate DNA in a test tube
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16
Q

Restriction enzymes

A

Cut DNA at highly specific points
Four to seven bases
Consistent results

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17
Q

Other enzymes

A 
First cut and then ligate
DNA ligase (putting back together)
   -Connects DNA fragments
DNA polymerase
   -Makes copies of DNA
   -Uses template
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18
Q

Gel electrophoresis

A

Separation of DNA fragments
Electrical current causes DNA to move towards positive electrode
Distance moved related to length of fragment

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19
Q

DNA hybridization

A

Formation of double -stranded nucleic acids
Labeled DNA probe
Binds only to complimentary DNA template

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20
Q

DNA sequencing

A

Allows identification of sequence of nucleotides in a DNA fragment
Automated sequencing machines–identify millions of bases/day

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21
Q

DNA cloning

A

Many identical copies of a gene or DNA fragment are made
Necessary for DNA manipulation
Sequencing, gene transfer, hybridization

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22
Q

DNA library

A

Collection of cloned DNA fragments
Restriction enzyme digestion
Plasmid–vector
Bacterium-host

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23
Q

DNA library–the screening process

A 
One is isolated from the many clones
Bacteria are plated on agar
Form colonies–each carries one gene
Screen by DNA hybridization
DNA probe for gene of interest
Isolate one colony and amplify
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24
Q

Polymerase Chain Reaction (PCR)

A 
Rapid amplification of DNA
Use a special DNA polymerase, resistant to high Temp
Cycles through three Temps:
             High-melting
             Low–annealing of primers
             Medium–polymerase extension
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25
DNA fingerprinting
* Identifies individuals - Forensics - Paternity test * Restriction Fragment Length Polymorphism (RFLP) analysis - DNA cut with restrictions enzymes - Gel electrophoresis - DNA hybridization - Compare bands
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Genetic engineering
Transferring genes between organisms v v Genetically modified organism (GMO) ``` Use of plasmids, viruses, or gene guns Changes the phenotype v v Faster growth Insect, herbicide, disease, or frost resistance Longer shelf-life ```
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Ethics–Where should the limits be drawn?
``` Bioengineering of bacteria, plants, dogs, ... humans? Pesticide resistance-more pesticide use? Bovine growth hormone-necessary? Human cloning-therapeutic, reproductive? Gene therapy–human bioengineering? ```
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Genetic engineering
1. ) DNA extraction 2. )Creating recombinant plasmid 3. )Propagating gene of interest through genetic engineering and DNA cloning
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Slides to go through in Lecture 14
Polymerase Chain Reaction (PCR) Reproductive animal cloning Some applications of DNA cloning Genetic engineering
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Rest of Lecture 13
Yupp
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Genetics
Gregor Mendel, the father of Genetics Published his work in 1866 The Mendelianum
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Somatic cells are diploid
Genotype: genetic makeup Phenotype: expression of a genetic trait/observable characteristics Diploid - -Two copies of each chromosome - -Homologous pair: paternal homologue and maternal homologue Haploid -reproductive cells have only one copy of each chromosome
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Alleles
Alleles: different versions of a given gene i: neither A or B Homozygote: same two alleles (AA or aa) Heterozygote: two different alleles (Aa) Human blood groups A, B, AB or O Three alleles of one gene IA: A type sugar IB: B type sugar
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Donor and acceptor
A, B, AB or O | Print SLIDE
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Allele
One of two or more alternative versions of a gene.
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Genotype
The genetic makeup of an organism; more specifically, the two alleles of a given gene that affect a specific phenotype in a given individual
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Heterozygote
An individual that carries one copy of each of two different alleles (for example, an Aa individual or a C^wC^r individual
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Homozygote
An individual that carries two copies of the same allele [for example, an AA, aa, or C^wC^w individual]
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Phenotype
The specific version of a genetic trait that is displayed by a given individual; for example, black, brown, red, and blond are phenotypes of the hair color trait in humans.
40
Genetic cross
When two individuals are mated P generation: parent generation F1 generation: first generation F2 generation: second generation
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Gene mutations
Different alleles originally arose from a mutation Mutations can be: -Harmful -Beneficial -Neutral
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Dominant allele
Allele that has exclusive control over the phenotype of an organism when paired with a different allele
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Recessive allele
An allele that does not have a phenotype effect when paired with a dominant allele.
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Basic patterns of inheritance
Mendel started with true-breeding plants | Recessive trait skipped a generation
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Summary of Mendel’s concepts
Alternative versions of genes cause variation in inherited traits Offspring inherit one copy of a gene from each parent An allele is dominant if it has exclusively control over the phenotype of an organism when paired with a different allele Two copies of a gene separate in meiosis and end up in different gametes Gametes fuse without regard to which alleles they carry
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Mendel’s first law:
Law of segregation | Punnett square
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Mendel’s second law:
Law of independent assortment
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Extensions of Mendel’s laws
Many alleles do not show complete dominance ``` Incomplete dominance Co-dominance Pleiotropy Epistasis Environmental effects Polygenic traits ```
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Incomplete dominance
Heterozygote is an intermediate
50
Co-dominance
Both alleles are expressed Seen in blood types IBIBorIBi:type B IAIB:type AB IAIA or IA i: type A ii: type O
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Pleiotropy
A single gene influences a variety of traits Ex.albinism - Absence or reduced production of melanin - Skin color - Vision problems
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Epistasis
``` Gene interaction affects the phenotype Alleles: BBorBb= black bb= brown cc= white ```
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Environmental effects
Internal and external conditions influence phenotype Temperature Chemicals Nutrition
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Polygenic traits
Trait is determined by two or more genes A continuous distribution Skin color height
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Homologous chromosomes
*Sex chromosomes Females have two X chromosomes (XX) Males have X and Y (XY) Y is very small with few genes *Autosomes The other 22 pairs of chromosomes are homologous
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Chapter 15 | What is evolution
What is evolution
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"Nothing in Biology Makes Sense Except in the Light | of Evolution"
BY Theodosius Dobzhansky
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LUCA
3.5-3.8 billion years ago
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The study of evolution
French naturalist Jean-Baptiste Pierre Antoine de Monet, Chevalier de [Lamarck] (1744-1829) English naturalist Sir Charles Robert Darwin (1809-1882) Giraffe
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Biological evolution
Charles Darwin Descent with modification A change in the genetic characteristics of a population of organisms over time
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A change in the population
Only populations can evolve, individuals cannot
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Mechanisms of evolution
*Individual variation exists Morphology: form and structure Biochemistry Behavior *Evolution occurs in two ways Natural selection Genetic drift
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Natural selection
Organisms with current favorable traits have a better chance at survival The longer an organism lives, the more reproductive opportunities it will have More offspring may be produced by these opportunities More organisms will now exist with this same favorable trait than in the previous generation Some snakes are resistant to toxin produced by newts Snakes have evolved to resist the toxin
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Genetic drift
Differences between organisms in reproduction or survival due to chance; random Environmental disturbances can cause genetic drift - Hurricanes - Volcanic eruptions - Clearing land for development - Overhunting a species Chance
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Impact of evolution Three major themes in biology Adaptation
Evolution results in three major themes in biology: 1. Adaptation: Any characteristic that improves the survival of an organism 2. Diversity: The result of speciation (production of species) 3. Shared inherited characteristics: Characteristics arise due to a common ancestry 1. Adaptation :Any characteristic that improves the survival of an organism It is the result of natural selection
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Impact of evolution Diversity
2. Diversity: The result of speciation A species is an organism that cannot reproduce with other species Speciation may be caused by geographical barriers
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Impact of evolution Shared inherited characteristics
3. Shared inherited characteristics: Shared features arise due to a common ancestry Homologous structures Vestigial structures
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Horses and Donkeys
They create a mule, the mule will be infertile because the horse and donkey are two different species. But they can have sex and have an embryo, but it will be infertile
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Impact of evolution Shared no inherited characteristics
Shared non-inherited characteristics Convergent evolution in similar adaptations These are considered analogous structures: Thorns on roses and cacti Wings on birds and insects
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Evolutionary tree
``` Evolutionary derived features Shared features from common ancestry Descendants share features Group of close relatives Each level has unique shared features ``` ``` Evolutionary convergent feature Shared features not from common ancestor Shared features evolved independently Example: Opposable thumb (pandaversuschimpanzee) ```
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Evidence for evolution: fossils
Fossil record Extinctions(either it may have evolved into a new species or died) Change in species
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Evidence for evolution: evolutionary history
Organisms contain evidence of their evolutionary history Vestigial structures Embryological development
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Evidence for evolution: independent lines of evidence
Homology between the DNA sequence; example: cytochrome C Enzyme for aerobic respiration Present in all eukaryotes Morphology similarity decreases, you begin to see a change in how one looks. DNA homology decreases
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Evidence for evolution: continental drift
The lungfish existed before the break-up of the super-continent, Pangaea Horses appeared in North America, ~5,000,000 years ago Fossils of horses in South America are younger than 3,000,000, the time when the land-bridge between the Americas was formed
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Evidence for evolution: Direct observation
``` Direct observations of genetic change in populations Artificial selection Farming crops Domesticated animals An example of how populations can change ```
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All the same species
``` Brassica oleracea( common wild mustard) From this comes : ``` ``` Kohlrabi Brussel Sprouts Cabbage Cauliflower Broccoli Kale ```
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Evidence for evolution: present day formation of species
Rapid evolutionary change due to environmental conditions Harsh conditions drive changes in the population Changes can be seen in our time
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Impact of evolutionary thought
Darwinian evolution had a major effect on religion Evolution versus creationism Understanding evolution has impacted technology Development and use of pesticides Antibiotics Gene therapy

Biology 100 (7 decks)

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