Final Flashcards
Mendel’s law of independent assortment
Two different genes will randomly assort their alleles during the formation of haploid cells
Mendel’s Law of Segregation
The two copies of a gene segregate (or separate) from each other during transmission from parent to offspring
Fundamental theory of heredity
Inheritance involves the passing of discrete units of inheritance, or genes, from parents to offspring
Dihybrid cross F2 generation ratio
9:3:3:1
Monohybrid cross
Mendel’s first experiments involved crossing two variants of the same characteristic
Asexual reproduction
Generates offspring that are genetically identical to a single parent
- cell division
Sexual reproduction
Two parents contribute genetic information to produce an unique offspring
A ___ is an organized representation of the chromosomes within a cell.
Karyotype
Diploid -
Have two “sets” of chromosomes
Members of a pair of chromosomes are called ___.
Homologs
Homologous pair of chromosomes
- nearly identical in size
- have the same bending pattern and centromere location
- have the same genes
What does asexual reproduction?
Bacteria
Amoeba
Yeast
Sister chromatid
Two copies of a replicated chromosome joined at the centromere to form a pair
In actively dividing cells, G1, S, and G2 are collectively known as ___.
Interphase
Interphase
G1 - cell prepares to divide
S - cell has twice as many chromatids as there are chromosomes
G2 - cell accumulates the materials that are necessary for nuclear and cell division
Mitosis
- prophase (nuclear envelope dissociates into small vesicles, the chromatids condense into more compact structures, centrosomes begin to separate, mitotic spindle apparatus is formed)
- prometaphase (centrosomes move to opposite ends of the cell forming spindle poles, spindle fibers interact with the sister chromatids, kinetochore microtubules grow from the two poles, two kinetechores on a pair of sister chromatids are attached to kinetochore MTs on opposite poles)
- metaphase (pairs of sister chromatids align themselves along a plane called the metaphase plate, each pair of chromatids is attached to both poles by kinetochore microtubules)
- anaphase (the connection holding the sister chromatids together is broken, each chromatid, now an individual chromosome, is linked to only one pole, kinetochore MTs shorten, polar MTs lengthen)
- telophase (cytokinesis, chromosomes reach there respective poles and decondense, the nuclear membrane reforms to form two separate nuclei, quickly followed by cytokinesis)
What does sexual reproduction?
Eukaryotic organisms
Haploid -
They contain a single set of chromosomes
Meiosis I
Prophase I (the chromosomes condense, the nuclear envelope breaks down, crossing-over occurs)
- leptotene (replicated chromosomes condense)
- zygotene (synapsis begins)
- pachytene (a bivalent has formed and crossing over has offered)
- diplotene (synaptonemal complex dissociates)
- diakinesis (nuclear membrane breaking apart, end of prophase I)
Prometaphase I
Metaphase I (pairs of homologous chromosomes move to the equator of the cell)
Anaphase I (homologous chromosomes move to opposite poles of the cell)
Telophase I (chromosomes gather at the poles of the cells, the cytoplasm divides)
Prophase II (a new spindle forms around the chromosomes)
Metaphase II (chromosomes line up at the equator)
Anaphase II (centromeres divide, chromatids move to the opposite poles of the cells)
Telophase II (a nuclear envelope forms around each set of chromosomes, the cytoplasm divides)
Penetrance -
Whether gene penetrates enough in order to express or not
Expressivity -
The degree to which the trait is expressed
X-linked -
This pattern involves the inheritance of genes that are located on the X chromosome
Sex-influenced inheritance
This pattern refers to the effect of sex on the phenotype of the individual
Sex-limited inheritance
This refers to traits that occur in only one of the two sexes
Lethal alleles
An allele that has the potential of causing the death of an organism
Incomplete dominance -
Occurs when the heterozygote has a phenotype that is intermediate between either corresponding homozygote
Overdominance
This pattern occurs when the heterozygote has a trait that is more beneficial than either homozygote
Codominance
Occurs when the heterozygote expresses both alleles simultaneously without forming an intermediate phenotype
Mitosis vs meiosis
- mitosis produces two diploid daughter cells
- meiosis produces four haploid daughter cells
- mitosis produces daughter cells that are genetically identical
- meiosis produces daughter cells that are not genetically identical
Evaluating the validity of a hypothesis
Scientific method
Chi square test
How are alleles dominant?
- gain-of-function - protein encoded by the mutant gene is changed so it gains a new or abnormal function
- dominant-negative - protein encoded by the mutant gene acts antagonistically to the normal protein
- haplosufficiency - loss-of-function, heterozygote does not make enough product to give the wild type phenotype
ABO blood type inheritance
- Type O people can only accept type O
- type O can donate to anyone
- mother A type A (IaIa Iai)
Not the father AB IaIb
Child O (need a little i from both parents)
Father could be A, B, O(ii)
Epitasis -
When the alleles of one gene mask the phenotypic effects of the alleles of another
Extranuclear inheritance
Involves genes in organelles other than the nucleus: mitochondria and chloroplasts
Maternal effect
An inheritance pattern for certain nuclear genes in which the genotype of the mother directly determines the phenotype of her offspring
How to identify center gene gene in 3-point cross
Map distance
Inversion -
A change in the direction of part of the genetic material along a single chromosome
Inversion loop must form
Robertsonian translocation
Familial Down syndrome
Most common chromosomal rearrangement in humans
Euploidy -
Variation in the number of complete sets of chromosomes
Occur occasionally in animals and frequently in plants
Aneuploidy -
Variation in the number of particular chromosomes within a set
Abnormal condition
Endopolyploidy -
Diploid animals sometimes produce tissues that are polyploid
Autopolyploidy -
Complete nondisjunction can produce an individual with one or more sets of chromosomes
Alloploidy -
A much more common mechanism for changes in the number of sets of chromosomes
Hardy-Weinberg
Given allele, find frequency of heterozygotes
Frequency of heterozygous carriers is 2pq
Phases of cell cycle
G1 (cell growth)
S (DNA synthesis)
G2 (cell growth)
Monosomy -
Having a diploid chromosome complement in which one chromosome lacks its homologous partner
Twin spots
Consist of two genetically different clones of neighboring cells in a background of normal cells
Photolyase
DNA repair enzymes that repair damage caused by exposure to ultraviolet light
Telomere
Essential part of human cells that affect how our cells age
Caps at the end of each strand of DNA that protect our chromosomes
Rho protein
Binds to the transcription terminator pause site, an exposed region of single stranded RNA after the open reading frame at C-rich/G-poor sequences that lack the obvious secondary structure
Transcription protein in prokaryotes
Nucleoside
A compound commonly found in DNA or RNA, consisting of a purine or pyrimidine base linked to a sugar
Chromosomes of ___ include how many…
Thousands
Diameter of a double helix
2nm
Function of DNA polymerase
To make DNA from nucleotides, the building blocks of DNA
Function of RNA polymerase
Enzyme that produces primary transcript RNA
Sigma factor
Protein needed only for initiation of RNA synthesis
Cis-acting elements
- DNA sequences such as the TATA box, enhancers, and silencers exert their effects only over a particular gene
- possibly far from the core promoter, are always found within the same chromosome as the genes they regulate
- “next to”
Trans-acting factors
- regulatory genes that bind to such elements
- “across from”
Enhancers -
Activating sequences
Needed to stimulate transcription
Silencers
DNA sequences that are recognized by transcription factors that inhibit transcription
Promoter
Provides a site for beginning transcription
Terminator
Specifies the end of transcription
Anticodons
3-nucleotide sequences that are complementary to codons in mRNA
Allolactose in lac operon system
The ability of the lac repressor to bind to the operator site depends on whether or not allolactose is bound to it.
Allolactose is the inducer
The binding of allolactose alters the function of lac repressor because it prevents it from binding to the DNA
Monogenic disorder short answer
-Cystic fibrosis
- Located on human chromosome 7
- encodes a protein called the cystic fibrosis transmembrane conductance regulator (CFTR)
(Regulates ion transport across the cell membrane)
- recessive disorder or humans
- a person must inherit two copies of a defective CF gene - one copy from each parent - to have the disease
- the mutant allele creates an altered CFTR protein that ultimately causes ion imbalance (leads to abnormalities in the pancreas, intestine, sweat glands, and lungs)
Oncogene
Mutant gene that promotes cancer
A higher expression of an oncogene may cause a higher rate of cell division
Tumor suppressor genes
A gene that functions to inhibit cancerous growth
A decrease in the expression of tumor suppressor genes may allow cancer to occur
Lysogenic cycle
Phage does not direct the synthesis of new phages and does not kill the bacterial cell that acts as its host
Can exist in dormant stage for a long time
If cII protein accumulates to sufficient levels
Holliday junction
A site where an unresolved crossover has occurred between two homologous chromosomes
Mediator
A protein complex that interacts with RNA polymerase II and various regulatory transcription factors
Depending on its interactions with regulatory transcription factors, mediator may stimulate or inhibit RNA polymerase II
Operator
A sequences of nucleotides in bacterial DNA that provides a binding site for a genetic regulatory protein
Lac repressor
Lac repressor
Protein that regulates the lac operon by binding to the operator site and repressing transcription
Shine-dalgarno sequence
A sequence in bacterial mRNAs that functions as a ribosomal binding site
Transposon
Type of transposable elements that moves via transposase
Simple transposition
Widely found in bacterial and eukaryotic species
Trp repressor
Trp operon is regulated by the trpR gene, which encodes the trp repressor protein
When tryptophan levels within the cell are very low, the trp repressor cannot bind to the operator site
Wobble
Rules that govern the binding specificity between the third base in a codon and the first base in an anticodon
Pedigrees
Open circle - female Open square - male Diamond - sex unknown Open with line through - deceased Open with no line - unaffected Filled in - affected
cross
When two distinct individuals with different characteristics are bred to each other
Basal transcription apparatus
The minimum number of proteins needed to transcribe a gene
DNA replication
- Topoisomerase II (DNA gyrase) travels in front of DNA helicase and alleviates positive supercoiling
- single-strand binding proteins
- RNA primers
- primase synthesizes rna strands by the linkage of ribonucleotide
- DNA polymerase responsible for synthesizing the DNA of the leading and lagging strands
Homologous recombination
Requires the participation of many proteins that catalyze different steps in the recombination pathway
Single-strand binding protein
Human antibodies
Proteins produced by the immune system of vertebrates
B cells
Most sequence variation in humans is due to..
SNPs
Chromosome structure
Centromere in middle
Chemical bonds in DNA
Sugar deoxyribose, a phosphate group and complementary nitrogenous base pairs
Sugar-phosphate backbone
Base pairs linked by hydrogen bonds
Insertion
Mutations in which extra base pairs are inserted into a new place in the DNA
Deletion
Section of DNA are lost or deleted
Frameshift
Insertions and deletions can alter a gene so that it’s message is no longer correctly parsed
Substitution
Mutation that exchanges one base for another
