bio I lab exam 3

Gene

a genetic factor (region of DNA) that helps determine a characteristic

Allele

one of two or more alternative forms of a gene

Genotype

set of alleles that an individual organism possesses

Phenotype

the appearance of a character

Karyotype

a picture of all condensed chromosomes inside a cell

karyotyping

number and type of chromosomes present

How many chromosome pairs do humans have?

23

Somatic cells are:

diploid

Germ/sex cells are:

haploid

Autosome

non-sex chromosomes

Barr bodies

highly condensed, inactivated X chromosome found in nucleus of somatic cells in female mammals; prevents overload of genetic material; causes tortoise shell coat pattern as random X-linked color genes are inactivated or activated

Nondisjunction

failure of proper separation of chromosomes either during meiosis I or II

What are the two types of viable autosomal nondisjunction?

Trisomy 21 (down syndrome) and Trisomy 18 (edwards syndrome)

Triple X syndrome

causes sterility in females

Klinefelter’s syndrome

the individual will develop into a male but he will have abnormalities in puberty with underdeveloped testes and a female appearance

Turner’s syndrome

the individual will be female but there will be no menstruation, no eggs, and no breast development

Jacob’s syndrome

The individual appears to be normal but there are problems with speech, coordination, weaker muscles, and behavioral problems

Down syndrome

trisomy 21; individuals are characterized by short height, stubby hands and feet, wide face, and intellectual disability

Edward’s syndrome

Trisomy 18; individuals have misshapen skull, overlapping fingers, heart defects, and mental development issues

DNA isolation: Homogenization

blending strawberries with detergent breaks apart the cell walls/membrane and denatures proteins (salt water draws water away and dish soap breaks down lipid bilayer)

DNA isolation: deprotenization

adding meat tenderizer will strip histones away from DNA

DNA isolation: precipitation

adding alcohol makes DNA insoluble so it comes out of the solution and can be isolated

Nucleotides are made of what?

Phosphate group, pentose sugar, notrogenous base

What are nitrogenous bases held together by?

hydrogen bonds

What is the sugar-phosphate backbone held together by?

covalent conds called phosphodiester bonds

What is antiparallel?

DNA

What is the main characteristic of purines?

They have 2 rings

Give examples of purines

adenine & guanine

What is the main characteristic of pyrimidines?

They only have one ring

Give examples of pyrimidines

cytosine, thymine, uracil

helicase

unzips DNA by breaking the hydrogen bonds between nitrogenous bases

single strand binding proteins

they keep the two strands of DNA from pairing back together

primase

lays down an RNA primer

DNA polymerase III

adds nucleotide in the 5’→3’ direction

leading strand: built continuously towards fork

lagging strand: build in fragments away from fork

okazaki fragments

short DNA segments that are joined together by DNA ligase

DNA ligase

joins the 3’ end of one fragment to the 5’ end of another fragment

DNA polymerase I

removes RNA primer at the beginning of each okazaki fragment and replaces it with DNA nucleotides

DNA characteristics

• ATCG

• double stranded

• deoxyribose

• 2’ carbon has H attached

RNA characteristics

• AUCG

• single stranded

• ribose (2’ OH group)

Central Dogma

DNA → RNA → protein

Transcription

process of going from DNA to RNA; DNA cannot leave nucleus but information gets transcribed into mRNA to carry the message

Transcription: Initiation

RNA polymerase binds to promoter region and unwinds DNA

Transcription: Elongation

1 side of DNA strand serves as a template called the coding strand

• moves from 5’ to 3’ and makes complementary mRNA

Transcription: Termination

the end of transcription where RNA polymerase reaches a stop sequence and releases the mRNA; DNA winds back together

Translation

mRNA gets turned into protein

• ribosomes are where translation occurs

Codon

3 consecutive nucleotides that code for 1 amino acid

Degenerate

more than one codon can code for the same amino acid

Initiation codon

AUG is always the start codon and it codes for methionine

Stop codons

UGA, UAA, UAG code for termination of translation

Translation: initiation

mRNA attaches to ribosome; ribosome finds start codon (AUG); a tRNA with the anticodon UAB brings methionine; the large ribosomal unit joins forming the initiation complex

Translation: Elongation

the ribosome moves along the mRNA one codon at a time; tRNAs bring the amino acids to match each codon

• A site: new tRNA enters

• P site: holds the growing chain

• E site: tRNA exits

peptide bond form between amino acids and chain grows

Translation: termination

ribosome reaches a stop codon (UAA, UAG, UGA) and the protein is released

allopatric speciation

a population forms a new species while geographically isolated from its parent population

sympatric speciation

a subset of a population forms a new species without geographic separation

Directional selection

shifts the overall makeup of the population by favoring variants at one extreme of the distribution

Disruptive selection

favors variants at both ends of the distribution

Stabilizing selection

removes extreme variants from the population and keeps intermediate types

Genetic drift

chance events that alter allele frequencies from one generation to the next in a population

Founder Effect

a few individuals become isolated from a larger population and establish a new population where the gene pool differs from the original

Bottleneck effect

a severe drop in population size resulting in some alleles being overrepresented, underrepresented, or not represented at all

gene flow

the transfer of alleles in or out of a population due to movement of fertile individuals/their gametes

gene

coding for a particular trait

allele

different variations of a gene

Gene pool

sum of genes within a population

homozygous

having the same allele for a gene, AA, aa

herterozygous

having different alleles for a gene, Aa, dominant allele is represented

allelic frequency

p- frequency of dominant allele

q- frequency of recessive allele

If its shown as a decimal it for allele frequency and if it’s a percentage it is genotype frequency

genotypic frequency

p²-frequency of homozygous dominant

2pq- frequency of heterozygous

q²- frequency of homozygous recessive

If its shown as a decimal it for allele frequency and if it’s a percentage it is genotype frequency

Order of Taxonomy

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

species

group of organisms that are able to reproduce and produce viable offspring

Domains

prokaryotes: bacteria, archaea

eukaryotes: eukarya

characteristics of prokaryotic cells

• DNA is circular

• no membrane bound nucleus or organelles

Domain Archaea

• extremophiles: live in extreme environments

• no peptidoglycan in cell walls

• some contain introns

Domain Archaea: Methanogens

• live below the mud in swamps

• create methane (reduce CO2 to methane)

• poisoned by oxygen (anaerobic)

Domain Archaea: Halophiles

• live in very salty places

• color is due to pigment called bacteriorhodopsin

• have simplest form of photophosphorylation

Domain Archaea: Thermoacidophiles

• live in areas with a pH of 2 and below

• live in temps above 60° C

Domain bacteria

• most have peptidoglycan in cell walls

• gram + = lots of peptidoglycan (violet)

• gram - = little peptidoglycan (pink)

• have chemotaxis and phototaxis

• divide by binary fission

• extra chromosomal DNA in plasmids

• can form endospores: cells able to withstand harsh environments)

flagella

whip like appendages extending from cell membrane that allow for movement

chemotaxis

movement in response to chemical gradients

phototaxis

movement in response to light

3 shapes of bacteria

bacillus, cocci, spirilli

arrangements of bacteria

• diplo: paired

• strepto: chained

• staphylo: clusters

3 types of gene transfer in bacteria

conjugation, transformation, transduction

conjugation

transfer of DNA between 2 bacteria cells which are temporarily joined; DNA transferred through tube (pilus)

transformation

process of taking DNA from external environment; DNA shed by other bacteria

transduction

transfer of DNA between prokaryotes by viruses; bacteriophages are viruses that infect DNA; it attaches to a cell and makes more bacteriophages but some chunk of DNA from host cell gets caught in new bacteriophages so when that bacteriophage infects a cell, it transfers DNA

Photoautotroph

• energy source: light (sun)

• carbon source: carbon dioxide

Chemoautotroph

• energy source: inorganics

• carbon source: carbon dioxide

Photoheterotrophs

• energy source: light

• carbon source: organic compounds

Chemoheterotrophs

• energy source: organic compounds

• carbon source: organic compounds

• majority of bacteria

obligate aerobe

requires oxygen (most bacteria)

facultative anerobe

can grow with or without oxygen, usually faster with it

obligate anaerobe

poisoned by oxygen

symbiosis

an ecological relationship between different species with are in direct contact with each other

Mutualism

A: (+), B(+), both benefit

Commensalism

A: (+), B: (0), A benefits, B is neither harmed or benefited

Parasitism

A(+): B(-):, A benefits, B is harmed

Ammensalism

A:(0), B(-), A is neither benefited or harmed, B is harmed

5 Kingdoms of Domain Bacteria

Proteobacteria, Chlamydia, Spirochetes, Gram + Bacteria, Cyanobacteria

Proteobacteria Subgroups

Alpha, Beta, Gamma, Delta, Epsilon