Bio Final Stem cells, gene, blood typing

Stem cells

undifferentiated cells with the ability to develop into specialized cells

Embryonic Stem Cells:

ESCs; extracted from the inner cell mass aka the embryoblast; can be grown almost indefinitely, can repair tissues, pluripotent, can become any cell including the placenta (not embryos); the issue with ESCs is that they would’ve become embryos & some think that life has already started (killing baby)

Adult Stem cells

ASCs; extracted from bone marrow, blood, skin, & liver cells; multipotent; used for regeneration of blood, skin, bones, cardiac cells etc, can help spinal injuries, type 1 diabetes, stroke etc; no controversy

Induced Pluripotent Stem Cells

some from immature skin cells; pluripotent; can differentiate into any cell type (not embryos) & can reprogram or fix damages cells/tissues; issue is that it can cause cancer

Totipotent

Can differentiate into any cell type including placenta, forming a complete organism

Multipotent

Type of adult/somatic stem cells that can differentiate into a limited range of specialized cells within a specific tissue or organ

Ex: hematopoietic cells (red, white blood cells, platelets)

Pluripotent

Can develop into any cell type, but not placenta, so cannot form new embryos \n Ex: muscle, nerve, bone, other tissues

Preformationalist Ideas:

* a small person called a homunculus lived in every sperm or egg

Blending Inheritance

* offspring are a blend of the characteristics of their parents

Mendelian genetics

coined the term “particulate”; said inheritance is particulate, the factors that are passed onto the next generation are specific factors that are not blended (some info from mom some info from dad)

**What were the advantages of using pea plants?**

* several variations are available
* Quick generation time
* Produce many offspring
* Capable of self fertilization (selfing)

mating (fertilization):

* removing pollen from anthers (male) and manually placing it on the stigma (female),

pollen will fertilize ovules

Selfing

take pollen from the another and place it on the stigma of the same flower

Cross Fetilization

removed anthers from one flower to prevent selfing & place pollen from a different flower on the stigma of the flower that had the anthers removed

Reciprocal crosses

each plant was used as both make (pollen donor) & female (pollen recipient)

Phenotype

outward expression of the genotype

Genotype

allelic makeup of an individual with respect to a single trait or set of traits; determines phenotype

Trait

observable physical features

Allele

different DNA, sequences of the same gene. Represented by a letter (P-purple p-white)

True breeding

mendel used; plants that when selfed yield offspring w/ same traits

Mutation

a change in DNA Sequence of a gene; insertion, deletion, diseases etc

Gene

specific sequence of nucleotides in DNA involved in synthesizing polypeptide

Locus(loci)

location of gene in a chromsome

Homozygous

two alleles at a locus are the same

Heterozygous

two alleles at a locus are different

Dominant alleles

traits that are expressed (observed) and can mask a recessive allele

Recessive alleles

traits that are masked

Hybridization

breeding individuals of different species

Test cross

testing an unknown genotype with a homozygous recessive gene, based on results you can determine if its homozygous dominant or heterozygotes

Parental generation (F1):

who/ what you start with; true breeding plant that are crossed

First filial generation (F2)

F1 gives rise to F2, generation that comes after F1

**Monohybrid vs Dihybrid Crosses:**

* hybrid refers to offspring of crosses between organisms, differing in one or more characters

Monohybrid:

when you consider only one character at a time mono=one ex purple & white colors

Dihybrid

looking at 2 different genes at the same time; use FOIL to determine genotypes Ex: RrYy= RY rY ry

Discontinuous variation

have distinct characteristics

Continuous variation

individuals show range of characteristics rather than distinct characteristics

Incomplete dominance

blending of traits; in a heterozygote, expression of 2 contrasting alleles so the offspring displays an intermediate phenotype (merging of both alleles)

Codominance

in a heterozygote, complete & simultaneous expression of both alleles

Sex linked traits

found on sex chromosomes, don’t determine sex characteristics, Y chromosomes only encode for males, X chromosomes has other gene that encode for other traits, probability of inheriting genetic mutations is higher in males

X linked traits

mutations in the genes on the X

Multiple allelism

one gene can have three or more possible alleles; since humans have one pair of each chromosomes, then we can have up to 2 different alleles; ex: human blood type

Antigens

glycoproteins on the plasma membrane of RBC; determines type of blood you have

Antibodies

modifed proteins produced by white blood cells that are created to neutralize foreign objects by attaching to a specific antigen; always going to have opposite antibodies to antigens

Agglutination

Antigen + antibody

Pheno: Type a

Geno: AA or OO

Pheno: Type B

Geno: BB or BO

Pheno: AB

Geno: AB

Pheno: Type o

Geno: OO

RH groups

antigen preset on plasma membrane of RBC

Rh negative

RBC’s lack the Rh antigen; genotype rr

Rh positive

Rh antigen is present on RBC ; genotype RR or Rr on RBC (dominant)

Erythroblastosis fetalis:

aka hemolytic disease of the newborn (blood cells will broken), type of anemia \n First pregnancy is uneventful \n Second pregnancy dangerous for baby as mom now has Rh antibodies and immune system will attack Rh+ babies \n Happens when dad is Rh + and mom is Rh-

Linked genes

an exception to the law of independent assortment; genes that are loacted very close tother in the same chromosome; usually inherited together

Pleiotropic genes

a gene that produces a protein that functions in many different parts of an organism; ex cystic fibrosis (autosomal recessive)

Epistasis:

the phenotype expression of one gene is influenced by another gene; “standing upon a gene” ex: coat color for labrador retrievers depends on the gene for the pigment plus a gene for pigment deposition into the hair

Polygenic traits

not going to have distinct categories; influenced by several genes, environment may influence the expression; ex: skintone, metabolism, height, hair color, eyecolor

Mendel:

monk & scientist, father of genetics, pea plant experiments, came up with laws of heredity

Miescher

first identifies DNA, coined the term DNA

Sutton & Boveri

proposed chromosome theory of heredity, “genes are the units of heredity & are found in chromosomes”

Morgan

“fly room”, he and his colleagues confirm the chromosome theory of heredity, shows chromosomes are responsible for heredity being passed, worked w/ Muller

Muller

shows that X-rays induce mutations, mutated flies

Chargaff:

developed “Chargaffs rules”; discovers that A=T & C=G; thought DNA is a repeating sequence with no obvious pattern

**Chargaffs Rule of Base Pairing**

discovered that within any DNA molecule: \n % adenine = % thymine Ex: if adenine is 30% then based on % cytosine = % guanine Chargaffs rule thymine = 30%

He also discovered that within a DNA molecule:

* uniform A-T & C-G base pair width is same (maintains shape of DNA molecule to form a

double helix)
* Pairing had a consistent width down the length of the molecule: maintains DNA structure

Hershey & Chase

demonstrated that DNA is the molecule responsible for heredity; use radioactive lab to prove DNA is responsible for heredity

Watson & Crick

responsible for showing the structure of DNA; propose the double helix structure

\- first model: 3 helices, nucleotides facing out, the structure was unstable

Maurice Wilkin

* developed the technique of X-ray diffraction

Rosalind Franklin

* preformed X-ray diffraction on crystallized DNA molecules



* Rosalind got the data needed to determine structure of DNA
* Rosalind figured out that DNA is either spiral or helical structure
* franklins 1951 X-ray diffraction showed that DNA had:
* Helical structure
* Two strands running in opposite directions
* Uniform width
* Phosphate groups were on the outside of the molecule

**DNA Structure:**

* deoxyribonucleic acid
* Has a 5 carbon deoxyribose sugar- means there is a pentose & it lacks oxygen in one of the carbo
* Has phosphate groups that make up the back bone of DNA along w the sugar
* 2 strands that run anti parallel held together by nucleotides by complementary base pairing
* The 2 nucleotides will be held together by hydrogen bonds- gives flexibility to open up molecule &

makes it stable & helps DNA break apart to replicate
* Strands twist around each other to form a spiral shaped double helix
* Strands run in opposite directions (5’ to 3’ & 3’ to 5’) -> this represents the # of carbon to which

phosphate group is bound

**How do bases pair up on DNA? What holds them together?**

A pairs with TC pairs with G

• Hydrogen bonds hold the complementary bases together in the double helix

1\.Initiation

* helic**ase** unwinds the double helix at the origin of replication- “unzipping enzyme”
* Single strand binding proteins bind to strands
* Topoisomer**ase** prevents supercoiling of strands- prevents from overwinding
* Prim**ase** synthesizes RNA primers (short, 5-10 nucleotides long)- flag you wave to start a race

2. Elongation

* helicase is still unzipping, strands that are already open have RNA primers & that signals DNA polymerase to come in


* DNA polymerase: adds DNA nucelotides to the template strand (both leading & lagging strands)
* Leading strand: nuelceotides continuously added in the 3’->5’ direction toward the replication fork
* Lagging strand: nucleotides are not added continuously; DNA template runs 5’->3’ from the

replication fork & since DNA is made 5’->3’ fragments of DNA are made, known as Okazaki

fragments
* DNA polyemerase removes primer nucleotides & replaces them w/ DNA nucleotides- proofreading

ability -> 99% proficiency
* DNA Ligase: joins & glues Okazaki fragments together to create a continuous complementary

strand

Termination

* replication forks run into each other or reach the end of the chromosome
* Telomeres: repetitive sequences at the end of chromosomes that extend the chromosome and

prevent coding regions of DNA from being cut off or deleted; some cells have telomeres that can add telomeres back on

**Telomerase activity reactivated resulted in**

DNA damage \n Reverse neurodegeneration \n improve organ function \n Essentially can help age related conditions

**Mechanisms of DNA repair:**

mutations due to errors in DNA replication can be repaired

Mutations: permanent damage inherited changes in DNA sequence- can occur during replication or damage from chemicals or other agents

* proofreading: DNA polymerase recognizes 99% of errors (enzyme that adds nucleotides)
* When a nucleotide escapes proofreading we have mismatch repair
* Mismatch repair: occurs after replication; enzymes scan for mismatches & they recognize them

b/c they have abnormal hydrogen bonding & in some cases the width of the helix is affected; enzymes will remove part of the strand that is mismatched & it will be re-synthesized

Induced mutations:

caused by external factors

Substitution mutations

one base is replaces by another

Transition substitution

a purine or pyrimidine is replaced by a base of he same kind

Transversion substitution

a purine being replaced by a pyrimidine or vice versa

somatic mutations

not passed to offspring

Germ line mutations

can be passed over generations

Silent mutation

doesn’t casue any harm, does not affect protein sequence

Loss of function mutation

codes for nonfunctional protein

Gain of function mutation

codes for a protein with a new fuction

Central Dogma:

a series of rules that tells you how information is going to flow \n • start w DNA & then other sequences are going to be transcribed

Transcription

the process of copying DNA into RNA, happens in nucleus of a eukaryotic cell (prokaryotic cells lack a nucleus & transcription occurs in the cytoplasm)

in DNA we have thymine, in RNA we have uracil (2 bases will change) \n

Translation

relaying information to make a polypeptide (leave nucleus, travels to cytoplasm, captures a ribosome in ER& then info will be relayed) (aka occurs on ribosomes in cytoplasm for all cells) \n Purpose of central dogma: to covert DNA to RNA to make a functional protein

Enzymes

biological molecules that act as catalysts & aid in DNA/RNA transcription/translation

Ribosomes

used for protein synthesis; found in the cytoplasm & attached to the ER; reads mRNA codons & assembles amino acids to create proteins

Cytoplasm

gel-like substance filling the cell interior; acts as a “cellular kitchen” where reactions occur; metabolism, protein synthesis, & cell signaling

Endoplasmic reticulum (ER):

a network of membranes within the cell; extends thru nucleus & into cytoplasm; involved in protein synthesis, lipid metabolism, etc; acts as a “cellular highway” for transporting materials

Promoter:

a control sequence of DNA that tells RNA polymerase where to start transcription & which strand to transcribe; “little flag”

Transcription factors:

can activate or inhibit expression of a gene by signaling the promoter; some genes turn on some genes turn off

RNA polymerase:

* binds double stranded DNA (@ the promoter) & unwinds the DNA
* “reads” the DNA template sequence
* Makes a complimentary mRNA copy of the template DNA
* Uses base pairing rules except A pairs with U (ex: DNA has “ATCGT”, RNA will put “UAGCA”), the

addition of bases to make the mRNA transcript is the process of elongation

Process simplified:

* if we put initiation & elongation together, we are in the nucleus & start w/ double stranded

DNA & going to make a single stranded mRNA
* DNA opens up, RNA polymerase comes in & unwinds DNA & is going to bring in

complementary bases & then we have the mRNA transcript being made
* This RNA is going to carry info to make a protein (RNA leaves nucleus thru nuclear pores &

goes into cytoplasm where translation occurrs )

Ribonucleic acid: RNA

* sugar: ribose; Carbon2 has a hydroxyl group •

attached
* Single stranded •
* Bases: Uracil instead of T •
* Function: carries & transfers genetic info •
* Bases can form hydrogen bonds
* RNA can fold into a 3D structure

Deoxyribonucleic acid: DNA

sugar: deoxyribose; carbon2 has a hydrogen attached

Double stranded Bases:A,T,C,&G Function: stores genetic info

Messenger RNA (mRNA):

1. contains a copy of the info encoded by a segment of DNA; DNA= cookbook, genes = cake recipe , cake= protein

Ribosomal RNA (rRNA)

composes the ribosome along w/ proteins; site of protein synthesis; aids in translating nucleotide info into a protein

Transfer RNA (tRNA):

carries the correct amino acid to the site of protein synthesis in the ribosome; RNA molecule contains specific 3-nucleotide code, each 3-nucleotide code is specific to an amino acid, 3-nucleotide code (codon) & the amino acid are at opposite ends of the tRNA

Codons

3-nucleotide code, total of 64