Biology 1001A Lecture Notes - Lecture 5: Homo Sapiens, Nucleosome, Small-C

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Biology Lecture 5 - Genomic Variation
Independent Study Outcomes
1. The meaning of C-Value.
- refers to the amount of DNA contained within a haploid nucleus (a gamete for ex)
- OR one half the amount in a diploid somatic cell of a eukaryotic organism
- expressed in picograms
- the terms C-value and genome size are sometimes used interchangeably (in some cases)
- in polyploids (cells and organisms that contain more than two paired, homolo-
gous, sets of chromosomes) the C-value may represent two or more genomes contained
within the same nucleus
- polyploidy is most common in plants
2. The “paradox” or “enigma” associated with C values.
- complex puzzle surrounding the extensive variation in nuclear (the evolution of the) genome
size among eukaryotic species
- at center of enigma is the observation that genome size does not correlate with organismal com-
plexity
3. The meaning of haploid (n) and diploid (2n).
- gametes are haploid - 23 chromosomes
- somatic cells are diploid - 46 chromosomes
4. The relationship between C and n as measures of genome size.
- C = n
5. The proportion of the human genome that codes for protein.
-
8.3a - Chromosomes are the Genetic Units Divided by Mitosis
- most eukaryotes have two copies of each type of chromosome in their nuclei
- chromosome is said to be diploid (2n)
-humans have 23 different pairs of chromosomes ~> diploid # of 46
chromosomes (2n=46)
-other eukaryotes only have one copy of each type of chromosome in their
nucleus, haploid (n)
-2n=32 and n=16
-some plants species have 3, four, or even complete sets of chromosomes in
each cell
- number of chromosome sets is called ploidy
- equal distribution of daughter chromosomes is called chromosome segregation
-since sister chromatids remain attached to each other at their centromeres
following DNA synthesis, the pair of them is still referred to as just one chro-
mosome
- two daughter cells can each receive eight chromosomes even though there were only eight
chromosomes in the original cell
15.3b - Genome Sequence Determination and Annotation Involves Obtaining
and Analyzing the Sequence of Complete Genomes
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Document Summary

Independent study outcomes refers to the amount of dna contained within a haploid nucleus (a gamete for ex: the meaning of c-value. Or one half the amount in a diploid somatic cell of a eukaryotic organism. Polyploidy is most common in plants: the paradox or enigma associated with c values. Complex puzzle surrounding the extensive variation in nuclear (the evolution of the) genome size among eukaryotic species. At center of enigma is the observation that genome size does not correlate with organismal com- plexity: the meaning of haploid (n) and diploid (2n). Gametes are haploid - 23 chromosomes: the relationship between c and n as measures of genome size. somatic cells are diploid - 46 chromosomes. C = n: the proportion of the human genome that codes for protein. 8. 3a - chromosomes are the genetic units divided by mitosis. Most eukaryotes have two copies of each type of chromosome in their nuclei. Chromosome is said to be diploid (2n)

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