genetics is the science of genes, heredity, and variation in living organisms
TRANSCRIPT
![Page 1: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/1.jpg)
GeneticsIntuition will tell the thinking mind where to look next.
- Dr. Jonas Salk (inventor of the Polio vaccine)
![Page 2: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/2.jpg)
Genetics is the science of genes, heredity, and variation in living organisms.
![Page 3: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/3.jpg)
Gregor Johann Mendel (July 20, 1822 – January 6, 1884) was a scientist and Augustinian friar who gained
posthumous fame as the founder of the new science of genetics.
![Page 4: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/4.jpg)
He was a German lad who grew up on the family farm in Austria. He joined the Monastery so he could have a free education. He persisted with his education through two illnesses which caused him to miss over a year of school.
![Page 5: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/5.jpg)
He conducted his study in the monastery's 2 hectares (4.9 acres) experimental garden.
![Page 6: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/6.jpg)
. Mendel demonstrated that the inheritance of certain traits in pea plants follows particular patterns, now referred to as the laws of Mendelian inheritance.
![Page 7: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/7.jpg)
The garden pea plant (Pisum Sativum) is self pollinating. This means that the pollen from a flower fertilizes the egg cells of the same flower. So, the seeds that are produced
have all their traits from one parent..
![Page 8: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/8.jpg)
In pollination the sperm cell in the pollen grain unites with the egg cell in the ovary to eventually become a seed for
a new plant.
![Page 9: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/9.jpg)
This self pollination led to true breeding plants. That is short plants produced seeds that grew into short plants,
etc.
![Page 10: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/10.jpg)
After some initial experimentation, he settled on seven traits to study: seed shape, flower color, seed coat, pod shape, unripe pod color, flower location and plant height
![Page 11: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/11.jpg)
To make crosses between different traits, Mendel would cut off the anthers of a flower and use a paint brush to
add pollen from a plant he wished to cross.
![Page 12: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/12.jpg)
Between 1856 and 1863 he tested some 29,000 pea plants. He discovered that ¼ of the plants were purebred
recessive alleles, ½ were hybrid and ¼ were purebred dominant.
![Page 13: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/13.jpg)
Each original pair of plants is the P (parental) generation.The offspring are called the F1, or first filial generation.The offspring of parents with different traits are called
hybrids.
![Page 14: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/14.jpg)
He felt that traits were passed on from the parents to the young.The factors that determine traits are called genes.Each gene had two different forms or alleles.The gene for height had an allele for Tall (T) and one for short (t)
![Page 15: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/15.jpg)
The allele for tall was dominant over the allele for short.If a plant had both alleles it would be tall but would carry
an allele for short.
![Page 16: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/16.jpg)
Mendal crossed the F1 plants (Tt) with each other to see if the allele for short (t) had disappeared.
He discovered that ¼ of the F2 plants were short
![Page 17: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/17.jpg)
For each F1 plant the alleles segregate when the gametes (eggs and sperm) are produced.
![Page 18: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/18.jpg)
Mendel realized that principles of probability could be used to predict outcomes in the crosses.
Probability concerns the likelihood that an event will occur
![Page 19: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/19.jpg)
The probability that several independent events will occur in a row is the product of their individual
probabilities.So, the probability of flipping two heads in a row is ¼.
![Page 20: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/20.jpg)
What is the probability of a family having 6 boys in a row?
What are the odds that the next child is a boy? Girl?
![Page 21: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/21.jpg)
Here is a family with 7 girls in a row then 6 boys in a row!
What is the probability of that?
![Page 22: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/22.jpg)
Punnett squares are used to determine probabilities in the outcomes of genetic crosses.
The genotype = the alleles that the organism has (i.e. TT or Tt or tt
The Phenotype represents how the organism looks (Tall or short)
![Page 23: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/23.jpg)
The larger the number of flips the more the odds approach 50/50.
The same is true in genetics. The number of boys and girls in the US is about the same but you can still have
families with all boys or all girls.
![Page 24: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/24.jpg)
Homozygous organisms have two of the same allele (HH or hh)
Heterozygous organisms have two different alleles for a trait
![Page 25: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/25.jpg)
Law of independent Assortment.Separate genes for separate traits are passed
independently of one another from parents to offspring
![Page 26: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/26.jpg)
Law of Segregation: When any individual produces gametes, the copies of a gene separate so that each
gamete receives only one copy (allele).
![Page 27: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/27.jpg)
Incomplete dominance occurs when the phenotype of the heterozygous genotype is distinct from and often intermediate to the phenotypes of the homozygous
genotypes.
![Page 28: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/28.jpg)
Codominance is a phenomenon in which a single gene has more than one dominant allele.
If someone is heterozygous for two codominant alleles they will express the phenotypes associated with both.
![Page 29: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/29.jpg)
Multiple Alleles – a situation where there are three or more forms of a gene for a trait. The organism still has
only two but there are three or more alleles in the population
![Page 30: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/30.jpg)
Polygenic traits – Traits that are produced by the interaction of several genes. i.e. skin color.
![Page 31: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/31.jpg)
Fruit Flies (Drosophila melanogaster) are nice to use for research because of their large and few (8) chromosomes, they are easy to care for, they breed quickly and they lay
many eggs.
![Page 32: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/32.jpg)
Physical Appearance of sexes
![Page 33: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/33.jpg)
Some Fruit Fly recessive traits
![Page 34: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/34.jpg)
Meiosis is a type of cell division necessary for sexual reproduction in eukaryotes, such as animals, plants and
fungi.In meiosis, the number of sets of chromosomes is cut in
half from two sets (diploid) to one set (haploid)
![Page 35: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/35.jpg)
Homologous chromosome is a set of one maternal chromosome and one paternal chromosome that pair up
with each other during meiosis. These copies have the same genes in the same locations, or loci, as one another.
![Page 36: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/36.jpg)
Gametes (sex cells) for Fruit flies must contain half the number of chromosomes (haploid or 4) if the adults are to
have 8 chromosomes.
![Page 37: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/37.jpg)
Meiosis is a kind of cell reproduction in which the number of chromosomes is cut in half.
![Page 38: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/38.jpg)
Meiosis occurs in two stages – meiosis I and meiosis IIPrior to Meiosis I each chromosome is replicated.
The replicated chromosomes pair up, maternal with paternal to form a set of four chromatids called a tetrad.
![Page 39: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/39.jpg)
Meiosis I Prophase IChromosomes become visible, crossing over occurs, the nucleolus disappears, the meiotic spindle forms and the
nuclear membrane disappears.
![Page 40: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/40.jpg)
Crossing over in Meiosis I Prophase ICrossing over is the physical exchange of chromosome
parts. This crossing over results in new combinations of alleles
for the offspring
![Page 41: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/41.jpg)
Animated Prophase I of MeiosisProphase I is the longest phase of meiosis, typically
consuming 90% of the time for the two divisions.
![Page 42: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/42.jpg)
Meiosis I: Metaphase IThe pairs of chromosomes (bivalents) become arranged
on the metaphase plate and are attached to the now fully formed meiotic spindle.
![Page 43: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/43.jpg)
Meiosis I: Anaphase IThe two chromosomes in each bivalent separate and
migrate toward opposite poles. Notice that the sister chromatids remain attached!
![Page 44: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/44.jpg)
Meiosis I: Telophase IThe homologous chromosome pairs reach the poles of the cell, nuclear envelopes form around them, and cytokinesis
follows to produce two cells.
![Page 45: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/45.jpg)
Meiosis I: AnimatedThe homologous chromosome pairs reach the poles of the cell, nuclear envelopes form around them, and cytokinesis
follows to produce two cells.
![Page 46: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/46.jpg)
Meiosis II: Prophase IIMeiosis II begins without any replication of the
chromosomes. In prophase II, the nuclear envelope breaks down and the
spindle apparatus forms.
![Page 47: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/47.jpg)
Meiosis II: Metaphase IIThe chromosomes become arranged on the metaphase plate, much as the chromosomes do in mitosis, and are
attached to the now fully formed spindle.
![Page 48: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/48.jpg)
Meiosis II: Anaphase IIThe centromeres separate and the sister
chromatids—now individual chromosomes—move toward the opposite poles of the cell.
![Page 49: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/49.jpg)
Meiosis II: Telophase IIA nuclear envelope forms around each set of
chromosomes and cytokinesis occurs, producing four daughter cells, each with a haploid set of chromosomes.
![Page 50: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/50.jpg)
Meiosis II - Animated
![Page 51: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/51.jpg)
One way meiosis generates genetic variability is through the different ways in which maternal and paternal
chromosomes are combined in the daughter cells.
![Page 52: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/52.jpg)
Another way meiosis generates genetic variability is through the process of crossing-over between maternal
and paternal chromatid pairs during prophase I
![Page 53: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/53.jpg)
Gamete formation in Males (Spermatogenesis)
![Page 54: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/54.jpg)
Gamete formation in Females (Oogenesis)
![Page 55: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/55.jpg)
Mitosis – 2 genetically identical diploid cellsMeiosis – 4 genetically different haploid cells
![Page 56: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/56.jpg)
Thomas Hunt Morgan. Many genes in the fruit fly were inherited together (linkage groups). The four linkage
groups corresponded to the four chromosomes of the flies
![Page 57: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/57.jpg)
If 2 genes are on the same chromosome are they linked forever?
The farther apart two genes are the more likely they are to be separated by a crossover in Meiosis.
![Page 58: Genetics is the science of genes, heredity, and variation in living organisms](https://reader036.vdocuments.mx/reader036/viewer/2022062516/56649e4b5503460f94b40077/html5/thumbnails/58.jpg)
The rate of crossing over allowed people to determine locations for many genes on the chromosomes of the fruit
fly.