Unit 4: Chromosome Discovery & Structure Flashcards
carried traits from one generation to the next
Mendelian “factors”
observed cells in various stages of division and recognized that chromosomal movement during mitosis offered a mechanism for the precise distribution of nuclear material during cell division
Walther Flemming
characteristics that are studied for the
transmission / inheritance of traits
Mendelian factors
recognized and explored the fibrous network within the nucleus – termed as chromatin or “stainable material”
Walther Flemming
Father of genetics
Gregor Mendel
̶provided the first evidence that germ cell chromosomes imparted continuity between generations
Theodor Boveri
his work on Ascaris embryos provided one of the first descriptions of meiosis
Theodor Boveri
one of the pioneers of embryology
Theodor Boveri
confirmed and expanded upon Boveri’s observations
walter sutton
described the configurations of individual chromosomes in cells at various stages of meiosis (testes of Brachystola magna)
walter sutton
Their experiments provided the physical basis of the Mendelian law of heredity – developed the “Chromosomal Theory of Inheritance
boveri & sutton
credited by creating the 1st genetic map where they link certain characteristics to a certain position in a chromosome
boveri & sutton
Discovery of sex chromosomes and association between specific genes and specific chromosomes
morgan & bridges
color
chroma
Experimentally demonstrated Chromosomal Theory of Inheritance
using Drosophila melanogaster – pioneered “Fly Room” experiments
Thomas Hunt Morgan
helped establish the chromosomal basis of heredity and sex
Calvin Bridges
Threadlike structures or “colored bodies”
chromosome
Made of protein and a single molecule of DNA
chromosome
body
soma
somatic cells
mitosis
maternal traits are carried by?
mitochondria
germ cells
meiosis
Factors that distinguish one species from
another
chromosome
T/F: Majority of diseases linked w/ nuclear genome
T
Enable transmission of genetic information from one generation to the next
chromosome
DNA + Proteins
Nucleosome
Ensure daughter cell retains its own complete genetic complement
chromosome in mitosis
Enable each mature ovum and sperm to contain a unique single set of parental genes
chromosome in meiosis
how many are the human chromosomes
44 autosomes & 2 sex chromosomes
Other DNA materials found in?
mitochondria
how many are the mitochrondrial DNA
37
the molecule of life
DNA
T/F: Approximately 20k to 25k genes code for proteins that perform most life functions
T
Replicated condensed chromosome with sister chromatids
Metaphase Chromosome
linking protein, controls contraction/relaxation of nucleosomes
H1
relaxed H1 = ____ chromatin
loose
condensed chromatin = contracted = _______
heterochromatin
controlled by H1
eochromatin & heterochromatin
̶- Central region
̶- Primary constriction where sister chromatids are linked
centromere
̶- Consists of several hundred kilobases of repetitive DNA
̶- Responsible for chromosome movement at cell division
centromere
Two identical strands which are the result of DNA replication
chromatids
T/F: Short & Long arms can be transcribed and translated
F, they do not get transcribed nor translated
designated as p (petite)
short / p arm
designated as q (queus) or g (grande)
long / q arm
where kinetochore microtubule attaches
centromere
Organelle located at the centromere region
kinetochore
̶- Microtubule organizing center
̶- Facilitates spindle formation
kinetochore
chromosome types
Based on number of centromeres
Based on centromere position
Based on Arms Ratio
▪ Single centromere
▪ Reliably transmitted from parental to daughter cells
monocentric
▪ lacks centromere
▪ genetically unstable because they cannot be maneuvered properly during
cell division and are usually lost
acentric
▪ Two centromeres
▪ also genetically unstable because it is not transmitted in a predictable fashion
dicentric
metacentric chromosomes
1, 3, 16, 19, 20 (biggest to smallest) (baby toddler nagsweet 16 at adult)
T/F: Acentric cannot be carried in cell division
T
- Middle; yielding arms of roughly equal length
- Centromere is centrally located
- 5 pairs in humans
metacentric
submetacentric chromosomes
2, 4-12, 17-18, X (bata nagteenager nagdebut at babae sya)
▪ Off-center centromere; “q” arm is
longer
▪ Unequal length of chromosome arms
▪ 13 pairs
submetacentric
▪ Very close to one end; yielding a
small short arm
▪ 5 pairs in humans
acrocentric
means peak
acro
Acrocentric is often associated with small pieces of DNA called _______, encoding rRNA
satellites
acrocentric chromosomes
13, 14, 15, 21, 22, Y
▪ Centromere at the terminal end
▪ Not found in humans
telocentric
T/F: Centromere location gives us a clue on the identification of chromosomes during karyotyping
T
T/F: Telocentric chromosomes may show in people with down syndrome.
T
what arm does not appear in a telocentric chromosome?
p arm
arms length of metacentric
1.0-1.69
arms length of submetacentric
1.7-3.0
arms length of subtelocentric
3.1-6.9
arms length of acrocentric
> 7.0
arms length of telocentric
not applicable
is reciprocal to the arm ratio. Its values can range from 1 (if S = L) to 0 (if S = 0)
S/L
It is the proportion of long arm respect with the whole chromosome, being
complementary to the centromeric index. Indeed, [L/(L+S)] + [S/(L+S)] = 1. Its values can range from 0.5 (if S = L) to 1 (if S = 0)
L(L+S)
also called centromeric index, it is the proportion of short arm respect with the whole chromosome. Its values can range from 0.5 (if S = L) to 0 (if S = 0)
S/(L+S)
it is the difference between the two (complementary) proportions L/(L+S) and S/(L+S). Hence, its values can range from 0 (if S = L) to 1 (if S = 0)
(L–S)/(L+S)
it was conceived in order to be complementary to S/L, indeed [(L–S)/L]+S/L = 1. Its values can range from 0 (if S = L) to 1 (if S = 0)
(L-S)/L
̶- Tip of each chromosome to protect chromatids
̶- Tandem repeats of the hexameric sequence ‘TTAGGG’
telomere
how many base pairs in ‘TTAGGG’
7 base pairs in repeat
̶Functions in preserving chromosome stability
- Preventing abnormal end-to-end fusion of chromosomes
- Protecting the ends of chromosomes from degradation
- Ensuring complete DNA replication
- Having a role in chromosome pairing during meiosis
longer/short telomere?
larger the margin of protection of chromosomes from degradation
longer telomere
longer/short telomere?
prone to degradation
short telomere
T/F: Individuals with longer telomeres have been reported to have a longer subsequent lifespan in some studies
of vertebrate species, with the predictive power of age per se being lower (12, 13)
T
type of chromosome that has fused 2 ends
ring chromosome
