Bio 251 Final Exam

What is genetics used for

Disease study and Transmission

Increase agricultural output

Pharmaceutical

Medicine

Crime Scene analysis

Environmental DNA

Branches of Genetics-Transmission

Basic principles of heredity and how traits are passed from one generation to the next

Branches of Genetics-Transmission Example

Disease

Breeding → Animals

Branches of Genetics- Molecular

chemical nature of the gene itself; how genetic info is encoded, replicated, and expressed

Branches of Genetics- Population

Genetic composition of populations and how that composition changes geographically and with the passage of time

How do we study genetics

By using model organism

Model organisms characteristics

reproduce quickly

easy to maintain in lab

observable over entire lifespan

many offspring

know DNA sequences

How long have humans been interested in genetics

• 12,500

  • domestication of plants and animals

• 4,000 years ago

  • artificial selection via selective breeding

History of Human Genetics- Pangenesis

each part of the body contains genetic information for that body

History of Human Genetics- Preformationism (1665)

inside the egg/sperm there exists a fully formed mino adult which simply enlarges

History of Human Genetics- Germ plasm Theory (1800s

cells in reproduce organs carry a complete set of genetic info that is passed to egg and sperm

Gene

Inherited genetic material or DNA sequence that codes for a protein and trait

What are the units of heredity

Gene

Allele

Alternate forms of a gene

Phenotype

physical trait

Genotype

set of alleles that determines a trait

Prokaryotes characteristics

Nucleus: No nucleus

Cell Diameter: relatively small

Genome DNA: circular DNA

Amount of DNA: one chromosome

Membrane bound organelles: none (typically)

Eukaryotes characteristics

Nucleus: Has a nucleus

Cell Diameter: relatively big

Genome DNA: linear DNA

Amount of DNA: multiple chromosome

Membrane bound organelles: has membrane bound organelles

Types of prokaryotes

Bacteria and Archaea

Types of Eukaryotes

Fungi, Plant, Animals, and Protists

Prokaryotes

DNA does not exist in the highly ordered/ packed arrangement (nucleoid location)

single origin of replication

Eukaryotes

Genetic material is surrounded in a nuclear envelope

DNA is closely associated with histones to form tightly packed chromosomes

Multiple origins of replication

What is Prokaryotic Cell Division called

Binary Fission

Binary Fission Steps

1. Replication Begins at origin of replication

2. chromosome duplicated

3. two origins of replication move to opposite sides of cell

4. SMC (Structural Maintenance Chromosome) complexes prevent tangling

5. New cell wall forms Can take as little as 20 mins

6. Over 2 billion cells in 24 hours

Homologous Chromosomes

chromosomes that are similar in size and structure

• carries genetic information for the same sett of characteristics

  • one set of chromosomes from each parent

Centromere

Attachment point fro spindle microtubules

Telomeres

at the tips of a linear chromosome

• gets shorter at each cell replication

• if they get too short it can cause cell death

Origins of replication

Location where DNA synthesis begins (replication)

Sister chromatids

two copies of a chromosome that are held together at the centromere

How to find the number of chromosomes in a cell

count the number of chromatid

Cohesion

protein that holds the chromatids together

• warps around the chromatids

Shugoshin

protects cohesin so chromatids stay together

Chromatid

one DNA molecule

Mitosis

separation of sister chromatids

Mitosis phases

Interphase

Prophase

Prometaphase

Metaphase

Anaphase

Telophase

Cytokinesis

Eukaryotic Cell Division: Interphase- G1/S

regulated decision point

What does G1 do in interphase

Cells grows

Eukaryotic Cell Division: Interphase- G1

G1: growth and proteins for cell division synthesized

Eukaryotic Cell Division: Interphase- G0

damage cells may enter G0 which is a non-dividing phase which creates cell death

Eukaryotic Cell Division: Interphase- G1/S checkpoint

determines if the cell has internal and external conditions to see if they have the necessary resources, growth signals, and DNA integrity to continue the cell cycle

what happens to the cell after the G1/S checkpoint

the cell is committed to dividing

Eukaryotic Cell Division: Interphase- S phase

The DNA duplicates

Eukaryotic Cell Division: Interphase- G2 phase

helps prepares the cell for mitosis

Eukaryotic Cell Division: Interphase- G2/M checkpoint

only allows the cell to passed if DNA is completely replicated and undamaged

Prophase

chromosomes are condense to form two chromatids

• mitotic spindles form

Prometaphase

nuclear membrane breaks down

• spindles attach the chromosome at kinetochore

Metaphase

Chromosomes align in center of cell

• cohesion begins to break down

Anaphase

Sister chromatids separate move to poles

Telophase

nuclear membrne reforms and chromosome decondense

Cytokinesis

• separation of cytoplasm

• results of Mitosis

• Two genetically identical cells that are identical to parent cell

• cells have full compliment of chromosomes

• each daughter cell has half of cytoplasm and organelle content

Synapsis

Close pairing of homologous chromosomes

Tetrad

Closely associated four sister chromatids of two homologous chromsomes`

Crossing Over

when chromosome segments from sister chromatids of one chromosome to the sister chromatid cross over of the synapsed chromosome

Where does crossing over happen

happens in prophase one of meiosis

Meiosis

production of haploid gametes that creates genetic variation

Meiosis Stages

Interphase

Prophase 1

Metaphase 1

Anaphase 1

Telophase 1

Interkinesis

Prophase 2

Metaphase 2

Anaphase 2

Telophase 2

Cytokinesis 2

Prophase One

nuclear membrane breaks down

• crossing over occurs following condensation of chromosomes and homologous chromosome pairing

Metaphase One

homologous pairs randomly align of center of cell

Anaphase One

• shugoshin protects cohesion

• Homologous chromosomes separate

• Move towards poles

Telophase One

• cytoplasm separates after chromosomes move to poles

• nuclear membrane begins to form

• chromosomes decondense

Meiosis Two- Interkinesis

Nuclear membrane reforms and decondense

Prophase two

• nuclear membrane breaks down

• chromosomes re-condense

• spindle fibers begin to form

Metaphase two

• spindle fibers attach

• individual chromosomes align at center cell

Anaphase two

• shugoshin breaks down

• cohesin breaks down

• sister chromatids separate

telophase two

• chromosomes move to poles

• nuclear membrane forms

Meiosis two results

• 4 daughter cells from one parent cell n

• number of chromosomes in daughter cells is half of parent cell

• each daughter cell is genetically unique

Five characteristics of model organisms

• easy to use in lab

• Fast lifecycle

• Genetic background known

• genetically diverse

• lots of offspring

Medel’s Model Organisms Study approach

• pea plants studying seven characteristics

  • binary characteristics

• conducted crosses of plants for seven years

• hypothesis based testing

Locus

location on a chromosome

heterozygous genes

two different alleles (Bb)

Homozygous genes

two copies of the same allel (BB/bb)

what do alleles contain

Alleles contains DNA squence

Monohybrid

organisms differ in one trait

Dihybrid

organisms differ in two traits

Principle of Segregation

• each individual diploid organism possesses two alleles for a characteristic

  • two alleles segregate when gametes are formed

  • one allele goes into each gamete

Where does Principle of Segregation happen

happens in anaphase

Concept of Dominance

• when two different alleles are present in genotype

  • only the trait encoded by one of them is observed in the phenotype

Dihybrid cross

parents differ in two traits

Principle of Independent Assortment

• genes that don’t influence each other during sorting of alleles into gametes

  • every possible combination of alleles for every gene is equally likely to occur

Probablity

likelihood of the occurrence of a particular even

• cN be used to predict outcomes of crosses

Multiplication rule

Probability of two or more independent events taking place together

• multiply independent probabilities

Example of multiplication rule

1/6 × 1/6 = 1/36

Addition rule

probability of any of two or more mutually exclusive events

• calculated by adding the probabilities of events

Example of Addition Rule

¼ + 1/2 = ¼ + 2/4 = 3/4

Binomial expansion

Formula: (p+q)^n

• p= probability of having the recessive trait

• q= probability of having the dominant trait

• n= number of offspring

Chi- square test

compares the observed and expected values based on phenotype using null hypothesis

Chi- Square Test Formula

χ² = Σ(O - E)²/E

• Σ: sum your terms

• O: observed count from cross

• E: expected count based on punnett square

Null Hypothesis

there is no significant difference between the observed and expected numbers of difference of the values

Degrees of Freedom

number of independent random variables involved

• formula: n-1

What do you do is the p-value is more than 0.05

accept the null hypothesis

What do you do is the p-value is less than 0.05

reject the null hypothesis