Exam 3 - HW Questions Flashcards
If fertilization is considered day 0, when do cells lose totipotence in human development?
Day 4 (Morula) and Day 7, before implantation
- At day 4, the Morula is still totipotent. At day 7, the blastocyst is made of cells that will become embryo and those that will be placenta. So it is now pluripotent. This means that totipotence was lost between Days 4 and 7.
Describe what each cell layer will become?
Endoderm: Respiratory and Gastrointestinal tracts
Ectoderm: Skin and Nerve Tissue
Mesoderm: Muscles and Skeletons
All cells in an organism have the same genome. What ways do they regulate this genome to create specific cell-types?
Cells can change which genes are available for transcription
Cells can regulate which mRNAs are translated
Cells can regulate which proteins are functional
Cells can regulate which genes are transcribed
If a genome re-anneals faster than another genome what can you conclude?
Can conclude that the genome that re-anneals faster has more repetitive DNA than the other genome.
What are telomeric repeat sequences?
Six-base repeating sequence TTAGGG that is related around 3,000 times
What is non-coding DNA?
Portion of an organism’s genome that do not code for amino acids.
What could lead to the evolution of new functions in a species?
Changes int he genome only affects the species if they are in gametic cells. Second, transposons can change gene sequence (and thus gene function) depending on where they are pasted, regardless of how the transposon was created.
(True/False), individuals with identical genomes, have identical phenotypes
False
What does DNA polymerase use to function?
Uses dATP as a nucleotide
Builds the new strand from 5’ to 3’
Reads template from 3’ to 5’
Uses a “guess and check” method to add nucleotides
What happens during DNA replication?
Helicaase uses ATP as an energy source
Primase uses ATP to build primers
Telomerase adds nucleotides to the original DNA template
Ligase uses a condensation reaction to make a single phosphodiester bond at each site of ligation
Which mitotic state do chromosomes condense using histones?
Prophase (Package chromosomes)
Which mitotic stage do microtubules shrink to pull chromosomes to the MTOC?
Anaphase (Away)
Which meiotic stage determines which combination of parental chromosomes will end up in each gamete?
Metaphase 1 + Anaphase 1
What nucleotide is most likely to form pyramiding dimers?
dTTP
What part of the DNA is broken in a double strand break?
Covalent bonds between the 3’OH of one nucleotide and the 5’ phosphate of the next nucleotide.
