Protein Synthesis and Meiosis Quiz Flashcards
Protein Synthesis
The process of reading the instructions in the DNA to make a protein
What are the inputs and outputs of transcription? What’s its location?
Input: DNA
Output: mRNA
Location: Nucleus
What are the inputs and outputs of translation? What’s its location?
Input: mRNA
Output: Protein
Location: Cytoplasm/Ribosome
Transcription Process
- RNA Polymerase binds to the DNA Promoter where transcription is to begin and unzips the gene that needs to be copied (“TATA box”). 2. RNA Polymerase uses complementary base-pairing rules to match RNA nucleotides with the exposed DNA nucleotides. 3. The completed mRNA molecule is released. 4. DNA zips back up and the mRNA leaves the nucleus and enters the cytoplasm.
Translation Process
- mRNA attaches to the small subunit of the ribosome. 2. Ribosome reads the mRNA codons in the 5’ to 3’ direction; starting at codon AUG. 3. tRNA molecules act like taxis to pick up and drop off the amino acids that match with the current codon being read off the mRNA. 4. tRNA’s continue to drop off amino acids, and the ribosome binds the amino acids together with peptide bonds
- When the “stop codon” is reached, the ribosome releases the completed protein.
Codon
A set of three nucleotides on mRNA made of the bases A, U, G, C.
Anticodon
The complementary three nucleotides that tRNA carries.
What is the start codon?
AUG
Where do the codon and anticodon meet?
On the ribosome
mRNA
Messenger RNA. Copies instructions in DNA and carries these to ribosomes in the cytoplasm.
tRNA
Transfer RNA. Carries amino acids to the ribosomes and mRNA.
Complementary Base Pairing Rule
A matches with U. C matches with G.
Where is mRNA located? Where is tRNA located?
mRNA is found in the nucleus and cytoplasm of the cell. tRNA is found in the ribosomes and cytoplasm of the cell.
What is the purpose of a promoter in transcription?
It acts as the binding sight for RNA polymerase, marking the start point on a DNA strand where transcription should begin.
Transcription Purpose
Carry the code/instructions out of the nucleus
Translation Purpose
Read/follow the instructions on the mRNA to make a protein
RNA Polymerase: Function and Location
Located in the nucleus. Transcribes DNA to mRNA by using complementary base pairing rules
Prophase I
Homologous chromosomes line up closely to form a tetrad (4 sister chromatids).
Chromosomes pair up and overlap. Crossing over = Maternal and paternal chromosomes overlap and exchange some DNA randomly. Since crossing over is random, this process results in random genetic variation in the resulting gametes.
Chromosomes thicken and condense, nuclear envelope begins to dissolve, centriole pairs begin to migrate to opposite poles, and spindle fibers begin to form between them.
Metaphase I
Tetrads line up in the middle of the cell.
Independent Assortment = maternal and paternal homologues line up on opposite sides randomly (they can face either pole). Therefore, when they separate, random genetic variation will occur again.
Anaphase I
Chromosomes pairs are pilled apart. Cell enlarges and elongates in preparation for division.
Telophase I
End of 1st division
Cleavage furrow forms to divide the cell in half
Cytokinesis occurs - results in 2 non-identical daughter cells.
DNA decondenses back into chromatin. The nucleus reforms and the spindle fibers dissolve.
Prophase II
Beginning of meiosis II. The nuclear membrane begins to dissolve. The chromosomes condense and thicken. The nucleus disappears. The centriole pairs migrate to opposite poles as spindle fibers form between them.
Metaphase II
Chromosomes line up in the middle of the cell. The orientation of sister chromatids at the equatorial plate is random, so they can face either pole. This means when they are separated there is random genetic variation.
Anaphase II
Chromosomes are separated and pulled apart. Cell elongates in preparation for division
Telophase II
Final stage – cytokinesis
Spermatogenesis, 4 sperm made. In oogenesis, 1 egg and 3 polar bodies are created. Has unique genetic material
Half the number of chromosomes.
DNA decondenses back into chromatin. The nucleus reforms. The spindle fibers dissolve.
Synapsis
The pairing of homologous chromosomes during prophase I of meiosis, forming a tetrad. This process facilitates genetic recombination through crossing over, leading to genetic diversity in the resulting gametes.
What does meiosis result in?
Four haploid daughter cells
Chromosome
A single structure of DNA
Chromatid
One half of a duplicated chromosome
Sister Chromatid
Two identical halves of a duplicated chromosome, connected by a centromere
Homologous Pair
Two chromosomes, one from each parent, that have the same genes
Tetrad
A group of four chromatids formed during meiosis when homologous chromosomes pair up
Meiosis Chromosome Counts (Before Interphase, After Interphase, After Meiosis I, After meiosis II)
Before interphase: 46 chromosomes and 46 chromatids
After interphase: 46 chromosomes and 92 chromatids
After meiosis I: 23 chromosomes and 46 chromatids
After meiosis II: 23 chromosomes and 23 chromatids
What are chromosomes called during Meiosis I? What are they called during Meiosis II?
Meiosis I: Homologous chromosomes
Meiosis II: Sister Chromatids
