Final Review Flashcards
Nucleotdies
Building blocks of DNA
Base pairs in DNA
A&T
C&G
Base pairs in RNA
A & U
C & G
Allele
An alternative form of a specific gene
Traits
Characteristics of an organism
Ex. a pea plant color, height, color of seed, etc.
Homologous chromosomes / homologs
Pair of chromosomes, one of which is from your mother and the other is from your father
One of the chromosomes in a pair of homologous chromsomes
Haploid
Refers to an organism of cells that contain 1 set of chromosomes
In humans this is our gametic cell
Diploid
Refers to an organism or cell that contains 2 sets of chromosomes
In humans, this is our somatic cells
Plant genome from seed to seedless
Diploids have seeds
Triploids do not have seeds
Sister Chromatids
Unit of two identical chromatids and a centromere
Homologous chromosomes
Pair of chromosomes, one of which is from your mother and the other is from your father
Homozygous
The same allele for a trait
Heterozygous
TWo different alleles for a trait
Dominant
AA or Aa
Genetic variation
The differences in inherited traits within a population
Mendelian ratios
Single trait ratios
Aa X Aa
- 25% AA, 50% Aa, 25% aa
-Genotypic ratio: 1:2:1
-Phenotypic ratio: 3:1
Two trait ratios
AaBb x AaBb
-phenotypic ratio: 9:3:3:1
Mendel’s law of independent assortment
Two different genes randomly assort their alleles during the process that gives rise to gametes
Dosage compensation
Refers to the phenomena in which levels of expression of many genes on the sex chromsome are similar in both sexes even though males and females have different sex chromosomes
Barr Bodies
Structure during the interphase nuclei of somatic cell of female mammals that is highly condensed X-X chromosome:
-XX has 1 barr body
-XY has 0 barr bodies
-XXY has 1 barr body
-XXX has 2 barr bodies
Z-W System
Bird sex determination
-ZZ = male (homogametic)
-ZW = female (heterogametic)
Feedback inhibition
Used to regulate / control enzymatic reactions, typically containing many steps
Can be positive or negative, most of the time it is negative feedback when we are talking about enzymes
Incomplete penetrance
This pattern occurs when the dominant phenotype is not expressed even though an individual carries a dominant allele
Ex. An individual with polydactyly allele (dominant) but has normal number of fingers
Incomplete dominance
This pattern occurs when the heterozygote has a phenotype that is the intermediate between corresponding homozygotes
Red=AA
White=aa
Pink=Aa
Codominance
Inheritance patterns occur when the heterozygote expresses both alleles simultaenously without forming an intermediate phenotype
Ex. AB blood type
Overdominance
When the heterozygote has a greater level of reproductive success than either homozygote
Ex. sickle cell anemia
Nondisjunction
Failure of chromosomes to separate correctly during anaphase
Trisomy
Contains an extra chromosome (2n + 1)
Ex. trisomy 21
Essential genes
Genes that encode for a protein that is considered necessary for survival
Nonessential genes
Not required for survival although likely beneficial
Lethal alleles
An allele that has the potential to cause death
Endosymbiosis
Describes a symbiotic relationship in which the symbiotic usually lives in the host
Ex. mitochondria and chloroplasts
Gene imprinting
Refers to a pattern of inheritance that involves a change in a single gene or chromosome during gametic formation.
Typically done by methylation
Maternal Effect
An inheritance pattern of certain nuclear genes in which the genotype of the mother directly determines the phenotype of her offspring
Snail coiling (maternal effect)
Based on mother genotype
Recombinant chromosomes
Refers to the combination of alleles or traits that are different than parents. It is a result of crossing over
What is the Hardy-Weinberg equation
p2 + 2pq + q2 = 1
p2=AA
2pq=Aa
q2=aa
Natural selection
The process by which differential fitness acts on the gene pool. when a mutation creates a new beneficial allele, the allele may become prevalent within the future generations, because the individuals with the allele will have greater reproductive success and survival
Genetic Drift
Mechanisms of evolution occurs when allele frequencies change over generations due to random chance
Translocation
When one segment of chromosomes becomes attached to a different part of the same chromosome
Can be an issue if the important genes that is euchromatin gets translocated to a section of heterochromatin which would cause the important gene to turn off
Terminal deletion
Loss of a segment from the end of the linear chromosome
Insertitial deletion
Loss of an internal segment from a linear chromosome
Paracentric inversion
Centromere lies outside of the inverted region
Pericentric inversion
The centromere lies within the inverted region of the chromosome
Concordance values
For Siblings: 0.5
Idetical twins: 1.0
Parent of offspring: 0.5
Aunt/uncle: 0.25
Grandparents: 0.25
Transduction
A virus that infects a bacterium and then transfers genetic material to bacteria
Conjugation
Involves a direct physical interaction between two bacterial cells one bacterium to another
Transformation
Is a process in which genetic material is released into the environment when a bacterial cell dies. this dead bacterial genetic material can then be taken up into the cell
Hfr
Has fertility factor plasmid completely integrated into the host genome and can NOT form a sex pilus
F+
Has a fertility plasmid not integrated into the host genome and can form a sex pilus
F’
Has fertility plasmid integrated into the host genome and rarely from a sex pilus
Prophage
Bacteriophage that integrates genetic material with the host genetic material
Virulent phage
A bacteriophage that only has a lytic cycle as a means of reproduction
Temperate phage
A bacteriophage that has both lytic and lysogenic cycles as a means of reproduction
Episome
A segment of DNA such as a plasmid that can replicate independently of the chromosomal DNA and can integrate into the chromosome
Reverse transcriptase
Used to convert RNA to DNA and used in viral integration like in HIV or in retro-transposition
HIV
RNA Virus
Gets converted to DNA using reverse transcriptase, then gets integrated into the host cell using integrase enzyme
The virus is prone to many mutations which makes it very hard to treat due to it begin an RNA virus
Transcription
Conversion of DNA to RNA
Can occur simultaneously with translation in prokaryotes (not eukaryotes)
Translation
Conversion of RNA to protein
Can occur simultaneously with transcription in prokayotes (not eukaryotes)
Conservative theory of DNA
After one round of replication, half of the new DNA double helices would be composed of completely old, or original, DNA and the other half would be completely new
Semiconservative theory of DNA
After one round of replication, every new DNA double helix would be a hybrid that consisted of one strand of old DNA bound to one strand of newly synthesized DNA
Dispersive theory of DNA
The original DNA double helix breaks apart into fragments, and each fragment then serves as a template for a new DNA fragment
Retrotransposition
A transposable element that moves via transposition > transcribed into RNA then reverse transcriptase makes a second copy in DNA
Levels of chromosome compaction
Nucleosomes
30mm fiber
Loop domains
Metaphase chromosomes
Helicase
Unzips the DNA
Topoisomerase
DNA Gyrase relaxes the supercoiling ahead of the replication fork
DNA polymerase II
Synthesizes the DNA in the leading and lagging strand
DNA ligase
Glues together the Okazaki fragments
Double stranded binding proteins
Holds up the double stranded DNA to form the replication fork (makes sure the DNA bein duplicated does not rejoin during the duplication process
Directionality and orientation of DNA
Always goes in the 5’ to 3’ direction when being synthesized. Is in the antisense confirmation
Complementary DNA
5’ ATCGATCG 3’ is complimentary to
3’ TAGCTAGC 5’
Introns
Non-coding sequences present in mRNA > do not lead to any protein production
Exons
Functional or coding sequences present in mRNA > leads to protein production (Gene expression)
Alternative splicing
The phenomenon that pre-mRNA can be spliced in more than one way. Allows you to make more than one gene product (protein) with just one gene
mRNA modifications
5’ cap and poly A tail
tRNA
RNA molecule that carries the amino acids that correspond to codons in the mRNA. A tRNA molecule has an anticodon to pair with specific tri-nucleotides sequences
Shine-Dalgarno sequence
Ribosomal-binding site that facilitates the binding of mRNA to the 30s subunit
Kozak sequence
Like the Shine-Dalgarno sequence but for eukaryotes
Mutation
A change in DNA sequence and must be inheritable
Genetic Testing
Genetic testing for individuals looking to see if there is a genetic abnormality
Genetic screening
Genetic testing for a population-wide. basis for genetic abnormalityA
Amniocentesis
A type of genetic testing (individual) where amino fluid is sampled to look at fetal genetic abnormalities
Environmental mutagens
Mutagens outside the body, include UV rays, Gamma Rays and X-Rays
CpG Islands
Clusters of Cytosine and Guanine associated with epigenetic via methylation of cytosines
Constitutive
Means to be expressed continuously at constant levels of expression
Repressor proteins
Proteins used in a negative feedback loops. Repress/prevent the transcription of certain genes
Tumor suppressor genes
Inhibit cell growth and division. Protect us from cancer
Oncogenes
Promote cell growth and division. Result in cancer
Beneficial mutations
Mutations that are good for an organism. Typically leads to better reproductive success
Conditional mutation
Mutations that depend on the environment like temperature
Deleterious mutation
Mutations that are not good, and can be detrimental to the organism
Silent mutation
Mutation in which the codon for an amino acid gets changed, but due to the degenerate nature of codons still codes fro the same amino acid
Euchromatin
Less condensed regions of chromosomes, transcriptionally active
Heterochromatin
Tightly compacted regions of chromosomes, generally transcriptionally inactive
Antisense RNA
An RNA strand that is complementary to mRNA (creates double-stranded RNA which prevents translation)
Mutagens
An agent that causes alterations in the structure of DNA
Methylation of Histones
Makes the DNA associate more with the histones (DNA is now more tight around the histones) Crates a closed chromatin conformation
Acetylation of histones
Makes the DNA associate less with the histones (DNA is now less tight around the histones) and helps to create open chromatin and conformation
Activators
Proteins taht bind to enhancer regions
Enhancers
Regions where activators bind
Repressors
Proteins that bind to the silencing regions
Silencers
Regions where repressors bind
