Unit 3 college bio

Explain why Mendel chose pea plants and how he became the “father of genetics”

he chose pea plants because they carry both male and female parts and are able to self pollinate. Mendel is the one who figured out how traits are passed on but no one listened until after he died

Describe how Mendel’s law of segregation and the law of independent assortment are related to the movements of chromosomes during gamete formation and fertilization.

The law of segregation means that the allele pairs separate or (segregate) and then come back and pair up randomly at fertilization. Law of independence means that the allele from one gene does not influence the allele from another gene.

Alelle

one of two or more DNA sequences occurring at a particular gene locus

Dominant gene

Capital letter represents this, refers to the allele that will mask the expression of the recessive gene when both are present 

Recessive gene

lower case letter, has to have two lower case letters to be present, is masked by a dominant gene

Genotype

complete set of genetic material. Can also be referred to as alleles. Represented by letters

Phenotype

he observable characteristics of an individual. Such as brown fur, blue eyes etc… 

Heterozygous

Aa or a mixture of the two. Or it means that the dominant one still carries the recessive. Also known as a carrier 

Homozygous

 AA or aa which also means “purebred” it means that its either completely dominant or completely recessive

Predict outcome ratios and probabilities for problems based on Mendelian patterns of inheritance.

Multuply the individual probabilities together. Say you have 2/4 things be white and ¾ things be male than your ratio is 6/16 things are white males

Autosomal dominant

one parent must have the trait. Dominant traits will not skip a generation 

Autosomal recessive

neither parent has to have to trait but the kids can still have the trait. Meaning that the parents have to be heterozygous

Incomplete dominace

blend together like a white flower and a red flower make a pink flower 

Codominance

phenotypes are both shown. So a white flower and a red flower mix and make a white and red flower

Explain how ABO blood types are examples of multiple allele inheritance and which blood type shows codominance.

ABO blood types are all examples of multiple alleles because they all are the same gyne “blood type” but they are all different alleles of that blood type. The AB blood type shows codominance because they both show up in the allele.

Polygeneic inheritence

Occurs when a trait is governed by two or more genes (each with their own set of alleles) such as skin color

Describe ways in which the environment can influence genetic traits

Sometimes the environment changes a gene due to things like nutrition and temperature. If someone doesn’t eat enough than even though they have the gene to be tall they won’t be able to grow as tall as they can because they arent getting the right nutrients. Or if plants have to have above 32 degree weather to grow white ones but it can grow red ones at that temp then there will be far more red ones than white ones.

Describe what is meant by the term *linkage group*

all the genes on one chromosome that tend to be inherited together

Autosomes

Chromosomes #1-22 that everything from eye color, to hair lenght, to height 

Sex-linked

Chromosome #23 that determines whether someone is male or female

Explain X-linked genetic inheritance - why males get more x-linked genetic disorders than females.

Only found on the X chromosome. Males get their x chromosome only from their mother. They have one X and one Y. So if the mom has a genetic disorder there is a 50-100% chance that the male will get the disorder because his mom had it.

Solve crosses involving sex-linked traits

Describe how chromosomes number disorders arise

these occur at random during the fermentation of the sperm or egg. 

Karyotype

chromosomes arranged by pairs according to their size and general appearance

Nondisjunction

Failure of chromosomes or sister chromatids to separate during meiosis 

Trisomy

a chromosome is present in three copies

Monosomy

a chromosome is present in one copy

Barr Body

an inactive X chromosome

Types of mutations

chromosomal and gene mutations

Types of chromosomal mutations

Duplication, Deletion, Inversion, Translocation

Deletion

occurs when a single break causes a chromosome to lose an end piece or when two simultaneous breaks lead to the loss of an internal chromosomal segment

Duplication

chromosomal segment is repeated in the same chromosome or in a nonhomologous chromosome

Translocation

involves the exchange of chromosomal segments between two nonhomologous chromosomes

Inversion

a segment of a chromosome is turned 180 degrees, reverse sequence of alleles can lead to altered gene activity

Types of gene mutations

Frame shift and point

Frame shift mutation

insertion or deletion, the worse kind of gene mutations because it moves every allele up or down one

Point mutation

has 3 different types; nonsense meaning it creates a stop codon, silent meaning that the codon doesnt change, and a missense meaning that it creates a different codon

Describe the structure of DNA

DNA is a chain of nucleotides and each nucleotide is a complex of three subunits that include a phosphate, deoxyribose, a nitrogen base. The two strands make up a DNA double helix. The strands are held together by hydrogen bonds between base pairing. **Complementary base pairing**: A goes to T and C goes to G

Explain why DNA replication is semiconservative

Each daughter DNA double helix consists of one new strand but then also still has one of the old strands. Meaning that it semi conserves the first strand

Helicase

opens or “unzips” the DNA by breaking the hydrogen bonds apart

RNA primer

lays down the rna for the first couple nucleotides so that the polymerase knows where to start

DNA polymerase

adds the new nucleotide strand by adding complementary base pairs and then joins these two together. Builds from the 5’ end to the 3’ end. This all happens normally with the leading strand, but with the lagging strand it works backwards and then goes back to the beginning. Making sure that it always follows the helicase

DNA ligase

connects okazaki fragments and seals breaks in the sugar-phosphate backbone

mRNA

the messenger, it carries the protein information from the nucleus to the cytoplasm

tRNA

transfer, serves as a link between the messenger RNA and the growing chain of amino acids

rRNA

ribosomal, direct the catalytic steps of protein synthesis

Transcription

takes place in the nucleus, a portion of the DNA serves as a template for mRNA formation. Takes the original DNA structure and turns it into mRNA. Begins when RNA polymerase binds to the promoter site. Then the DNA helix is opened so base pairing can occur. RNA polymerase adds the complementary base pairs but uses U instead of T.

Translation

 takes place in the cytoplase, sequence of mRNA bases (complementary to those in the template DNA) determines the sequence of amino acids, tRNA assist by bringing amino acids to the ribosome.

3 stages of translation

Initiation, Elongation, Termination

Initation

mRNA comes in and gets a small ribosome, tRNA and a large ribosme added to it

Elongation

 mRNA codes for an amino acid and it gets attached to the tRNA, moving down the mRNA each time making the polypeptide chain longer

Termination

mRNA codes for a stop codon and it releases the polypeptide chain

Promoter

a region of DNA where RNA polymerase begins to transcribe a gene

Exons

nucleic acid coding sequences, found in mRNA

Introns

non-coding sequences that ger removed before translation

Gene

sections of DNA that contain a set of instructions to produce one specific molecule in your body

Codon

a sequence of three nucleotides that forms a unit of genetic information. The codon then codes into an amino acid. Such as AUG codes for MET

Anticodon

a sequence of three nucleotides located at one end of a tRNA molecule which is complementary to the corresponding codons in mRNA. Allow the mRNA to connect to the tRNA

Determine the sequence of amino acids in a protein, given the messenger RNA sequence

* Example: TACCCTAGATTTATC ----> AUGGGAUCUAAAUAG -----> MET-GLY-SER-LYS
* Takes it from DNA changes it to mRNA and changes that into amino acids 
* Use the star chart to figure out the amino acid

Describe the relationship between gene regulation and gene activity in a cell

**Gene regulation** is how a cell controls which genes are “turned on” or expressed. And because of this each cell has a different set of active genes or “turned on” genes.

Operator

a sequence of DNA where RNA polymerase attaches and transcription begins

Active Repressor

binds to the promoter and stopping transcription

Pretranscriptional Control

eukaryotes use DNA methylation and chromatin packing as a way to keep genes turned off.

Transcriptional Control

eukaryotic transcriptional control is dependent on the interaction of protiens with particular DNA sequences

Posttransprictional Control

following transcription, mRNA is processed before it leaves the nucleus and passes into the cytoplasm

Spontaneous mutations

due to abnormalities in normal biological processes

Induced mutations

enviromental influences

gene mutations

a permanent change in the sequence of bases in the DNA

Mutagens

enviromental influences called mutagens cause mutations in humans. Such as radiation or X'-rays

Transpoons

specific DNA sequences that have the remarkable ability to move within and between chromosomes

Describe why cancer is a failure in genetic control

If a person has an error in DNA repair that means that mistakes remain uncorrected and they become mutations such as cancer

Characteristics of a cancer cell

Genetically unstable, do not regulate the cell cycle, escape the signals for cell death, can survive elsewhere in the body

Explain what is meant by a DNA “fingerprint”

During a process called gel electrophoriesis, whereby an electrical current is used to force DNA through a porous gel material, these fragments are seperated according to their size. Smaller fragments move farther through the gel than larger fragments, and result in a pattern of distictive bands.

Explain why STRs may be used for identification

STRs are short tandem repeats that are the same short sequence of DNA bases that recur several times, such as GATAGATAGATA. these show in the gel electrofercies

What is a PCR

it is used to allow humans to duplicate DNA

What are the 3 stages of PCR

Denature, Annealing, Extension

Denature

heats up the DNA so it can seperate

Annealing

allows us to be able to lay down primer

Extension

builds the nucleotides like a polymerase

What is recombinate DNA

where a gene is cut out with the use of a restrictive enzyme and placed into a vector which was taken out of a bacteria. One the gene is placed into the vector it then goes back into the bacteria which then goes through mitosis and duplication making the creation of the specific gene protien to be amplified