Dispense VERIFICATO
biologia
16 visualizzazioni
20 download
Nessun voto ancora
Di cosa parla
- Microtubule Assembly: Microtubules form from alpha and beta tubulin heterodimers, which polymerize into oligodimers, then protofilaments (13 forming a hollow tube).
- Autosomal Dominant Segregation: Character frequency is equal in both sexes, appears in every generation, affected individuals have affected parents, and there's a 50% chance for offspring if one parent is affected.
- Eukaryotic Gene Sequence: Correct sequence from 5' is promoter-exon1-intron-exon2-nonsense-triplet-3'. Poly A is added post-transcription.
- Amino Acid Calculation: A given RNA sequence 5'-GAU-AUU-AUG-AUU-GUA-UUU-AUG-AUU-GUA-UAA-AGU-3' codes for 7 amino acids, counting from AUG (start) to UAA (stop, non-coding).
- Transcription vs. Replication: Replication duplicates DNA, while transcription produces mRNA for gene expression.
- Genetic Map Distance: A 20% crossing over frequency (2 out of 10 meioses) corresponds to a 10 cM map distance (20%/2).
- Nucleosome Structure: Composed of a histone core (H3/H4 tetramer and H1/H2 dimer), H1 histone, and DNA (core and linker), with H1 compacting the DNA.
- Chromosomes in Mitosis (Somatic Cell): In profase, telofase (daughter cells), and G2 phase, a human somatic cell always has 46 chromosomes. DNA quantity varies (doubled in G2/prophase).
- Gamete Production: For a heterozygous AaBb individual:
- Cis configuration (AB/ab): 50% AB, 50% ab.
- Trans configuration (Ab/aB): 50% Ab, 50% aB.
- Independent assortment: 25% AB, 25% Ab, 25% aB, 25% ab.
- Activators and Repressors: Regulatory proteins that either inhibit or promote gene transcription and expression.
- Monosomy: A chromosomal number mutation (2n-1 = 45 chromosomes), compatible with life only for specific chromosomes.
- Balanced vs. Unbalanced Mutations: Balanced mutations have no phenotypic effect, while unbalanced mutations do.
- Dominant Autosomal Disease Risk: For a parent with an autosomal dominant disease (incomplete penetrance) and a de novo mutation, the transmission risk to a child is 50% if the parent is heterozygous, 100% if homozygous dominant (assuming a healthy partner).
- Exceptions to Mendel's Laws:
- Lethal Alleles: Alleles coding for essential proteins, causing death in specific genotypes.
- Codominance: Both dominant alleles are expressed simultaneously in heterozygotes.
- Incomplete Dominance: Heterozygote phenotype is an intermediate blend of the two homozygous phenotypes.
- Endosymbiotic Theory Evidence: Mitochondria have internal membranes similar to bacteria, ATP synthases like bacterial mesosomes, their own DNA and ribosomes, and replicate independently.
- Test Cross (Rincrocio): A procedure to determine if an individual showing a dominant phenotype is homozygous or heterozygous by crossing them with a homozygous recessive individual. If recessive offspring appear, the dominant parent was heterozygous.
- X Chromosome Inactivation: In women, one X chromosome is inactivated (lyonization) to balance gene dosage, as women have two X chromosomes. This process is random, reversible during meiosis, and stable in somatic cell lineages.
- Recombination Frequency: If crossing over occurs in every meiotic cell for a dihybrid organism, the recombination frequency is 50%.
- Restriction Enzymes: Enzymes that cut DNA segments. Exonucleases cut from ends, endonucleases cut internally.
- Aneuploidy and Polyploidy:
- Aneuploidy: Chromosomal number mutations (gain or loss of 1 or 2 chromosomes, e.g., monosomy 2n-1, trisomy 2n+1, tetrasomy 2n+2). Compatible with life for certain chromosomes.
- Polyploidy: Chromosomal number mutations involving entire sets of chromosomes (e.g., triploidy 3n, tetraploidy 4n). Generally not compatible with life.
- Plasmids: Circular DNA segments found in bacteria that replicate independently of the bacterial chromosome.
- Hemophilia A Pedigree Analysis: Based on the provided pedigree for X-linked recessive hemophilia A, the probability for individual IV-1 to be affected is stated as 50% in the document. However, interpreting the pedigree directly suggests that if IV-1's mother (III-2) is affected (XhXh) and the father is unaffected (XHY), then all sons (like IV-1) would be affected, implying a 100% probability.