Chapter 3: Protein Synthesis And Cell Division Flashcards
Gene
Segment of DNA that codes for one protein. Exons part of gene that codes for amino acids. Introns non coding segments
Genome
Complete set of genes
Nitrogen bases
Adenine, guanine, thymine, cytosine. Uracil in RNA
Where does protein synthesis occur
In the nucleus
Three types of RNA
mRNA, rRNA, tRNA
Where does transcription occur
In the nucleus. Genetic info encoded in DNA, copied to strand if mRNA, mRNA is processed before leaving the nucleus
Where does translation occur
Outside the nucleus at ribosomes. mRNA to polypeptide then to 3d protein
tRNA
Carries amino acids to ribosome. Anticodon
What are the two major phases in the cell cycle
Interphase - cell growth, cell continues normal activities
Cell division (mitotic phase) - cell divide
A
Interphase
Nuclear matter in chromatin state, DNA must be duplicated
What stage is helicase present in
Interphase during dna replication. Unwinds dna helicases. In semi conservative replication dna polymerase adds nucleotides to form both new strands lagging and leading
Which cells don’t divide efficiently
Skeletal, cardiac, and nerve. Damaged cells get replaced with scar tissue.
Which cells cannot divide and why
Red blood cells because they don’t have a nucleus
What are the two distinct events of the mitotic phase
Mitosis and cytokinesis. 2 sets of chromosomes distributed into 2 separate nuclei.
4 stages of mitosis
Prophase (chromatin to chromosomes, centrioles pull chromosomes apart to opposite sides)
Metaphase (centromeres of chromosomes line at metaphase plate)
Anaphase (separate copies, start to furrow)
Telophase( two identical cells)
Prophase
Chromatin to chromosomes. Nuclear membrane dissolve. Centrosome to opp. Side
Anaphase
Centromeres of chromosomes split. Sister chromatids move to opposite poles
Metaphase
Centromeres of chromosomes line up at metaphase plate
Telophase
Mitotic spindle dissolves. Chromosomes regain chromatin appearance. New nuclear membrane
Cytokinesis
Cleavage furrow. Cytoplasm of parent cell fully splits. Interphase begins after
Apoptosis
Programmed cell death, normal. When cells are old or worn out. An be triggered by immune system
Necrosis
Abnormal cell death, irreversible. Cell injury, decreased blood flow, decreased oxygen levels. Adjacent cells can be damaged from bursts
Three possible destinies of cells
Remain functioning and no divide
Grow and divide
Die
Go signals for cell division
Critical to surface to volume ratio of cell chemical,s
Stop signals for cell division
Availability of space. Normal cells stop dividing when they contact other cells
When does unregulated cell division occur
Cancer
Meiosis
Only in gonads. Sexual reproduction. Reduces number of chromosomes in gametes by half so the zygote dos t end up with twice chromosomes
Haploid
Single set of chromosomes. 23 in humans. Occurs in gametes, only one member of each homologous pair sorry and eggs are haploid
Diploid
2 sets of chromosomes, 46 in humans. Sperm plus egg is zygote which is diploid
Homologous pair of chromosomes
Look alike and carry same genes for same traits
Sister chromatids
Each duplicated chromosome from interphase has two sister chromatids thatre identical and joined by centromere
No sister chromatids
Exchange dna with each other crossing over, during prophase one in meiosis, increases genetic variability
How many haploid cells result from meiosis
4 haploid
Meiosis one
Chromosomes from 2n to n. Crossing over in prophase one, at end each cell has half the number of chromosomes but each chromosome still has two sister chromatids which is double dna
Meiosis two
Separation of sister chromatids of chromosomes. Chromosomes not replicated before. Haploid not diploid.
What happens to cells as we age
Cells deteriorate in ability to function normally and respond to stress. Responses slow or ineffective. Number decreases. Lose integrity of extracellular components. Accumulation. Of free radicals and other toxins
