Unit 4: Chromosome Discovery & Structure Flashcards by JULIA CASSANDRA RECCION

carried traits from one generation to the next

Mendelian “factors”

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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

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characteristics that are studied for the
transmission / inheritance of traits

Mendelian factors

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recognized and explored the fibrous network within the nucleus – termed as chromatin or “stainable material”

Walther Flemming

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Father of genetics

Gregor Mendel

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̶provided the first evidence that germ cell chromosomes imparted continuity between generations

Theodor Boveri

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his work on Ascaris embryos provided one of the first descriptions of meiosis

Theodor Boveri

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one of the pioneers of embryology

Theodor Boveri

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confirmed and expanded upon Boveri’s observations

walter sutton

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described the configurations of individual chromosomes in cells at various stages of meiosis (testes of Brachystola magna)

walter sutton

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Their experiments provided the physical basis of the Mendelian law of heredity – developed the “Chromosomal Theory of Inheritance

boveri & sutton

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credited by creating the 1st genetic map where they link certain characteristics to a certain position in a chromosome

boveri & sutton

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Discovery of sex chromosomes and association between specific genes and specific chromosomes

morgan & bridges

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color

chroma

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Experimentally demonstrated Chromosomal Theory of Inheritance
using Drosophila melanogaster – pioneered “Fly Room” experiments

Thomas Hunt Morgan

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helped establish the chromosomal basis of heredity and sex

Calvin Bridges

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Threadlike structures or “colored bodies”

chromosome

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Made of protein and a single molecule of DNA

chromosome

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body

soma

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somatic cells

mitosis

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maternal traits are carried by?

mitochondria

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germ cells

meiosis

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Factors that distinguish one species from
another

chromosome

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T/F: Majority of diseases linked w/ nuclear genome

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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

the molecule of life

DNA

T/F: Approximately 20k to 25k genes code for proteins that perform most life functions

Replicated condensed chromosome with sister chromatids

Metaphase Chromosome

linking protein, controls contraction/relaxation of nucleosomes

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

- 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/F: Telocentric chromosomes may show in people with down syndrome.

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

1. Preventing abnormal end-to-end fusion of chromosomes 2. Protecting the ends of chromosomes from degradation 3. Ensuring complete DNA replication 4. 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)

type of chromosome that has fused 2 ends

ring chromosome

Unit 4: Chromosome Discovery & Structure Flashcards

(81 cards)