The Physical Basis of Heredity Flashcards
Genetics VS Hereditary vs Variation
GENETICS: study of heredity and variation
HEREDITY: transmission of traits from gen to gen
VARIATIONS: genetic differences between organisms within a species
What is the PROCESS involved in heredity and variation?
cell division
2 main components of the NUCLEUS in EUKARYOTIC CELLS
- nucleoli (ribosome-producing organelle)
- chromatin (granular network of complex DNA)
GENES
- _____ factors
- made of ____
- determines ___
heritable
DNA
traits
CHROMOSOME
- kind of structure
- composition
- carries ____
- cellular structure
- long DNA molecules
- carries genes
Main Parts of the CHROMOSOME (4)
- Chromatids (1)
- Centromere (2)
- Telomere (1)
- Kinetochore (1)
- One of the two identical halves of a chromosome
- Joins sister chromatids together
Region where spindle fibers attach during cell division (via the kinetochore) - Repetitive DNA sequences at the ends of chromosomes to protect against damage and uncoiling
- Large protein assemblies that help spindle fibers attach to the centromere
Types of Chromosomes BASED ON CENTROMERE (4)
- Telocentric (walang chromatid sa taas) - TERMINAL
- Acrocentric
- Submetacentric
- Metacentric (fully may chromatid) - MEDIAN
CHROMOSOMES
p-arm VS q-arm
p-arm SHORT ARM
q-arm LONG ARM
What are HOMOLOGOUS pairs?
A pair of chromosomes with the same length and set of genes
BUT from each of the 2 parents
what are SISTER CHROMATIDS?
a pair of chromosomes from duplication during S phase
Suffix to denote if chromosome is from:
- mother
- father
Chromosome 1:
1m
1p
What is Ploidy level?
no. of sets of chromosomes in a cell/organism
PLOIDY LEVEL IN:
- sex cells
- somatic cells
- haploid (one set)
- diploid (two sets)
no. of chromosomes in a human
46
2 main phases in the cell cycle
- Interphase
- M phase
INTERPHASE SUBPHASES
- G1 (4)
- S phase (1)
- G2 (2)
G1:
- acquires more water and nutrients
- active protein synthesis
- organelles double
- chromosome is stretched
S:
- DNA and chromosomes are duplicated
G2:
- active protein synthesis in preparation for M phase
- chromosome is folded once again
M (mitotic) PHASE - 2 subphases and their definition
- Karyokinesis (division of nucleus; 4 phases)
- Cytokinesis (division of cytoplasm)
Types of cell that undergo mitosis
somatic cells
Types of cell that undergo meiosis
germ cells
(not SEX CELLS kasi sex cells are mature na)
PROPHASE (3)
METAPHASE (2)
ANAPHASE (2)
TELOPHASE (3)
Prophase:
- chromatin condenses
- nuclear membrane disintegrates
- spindle fibers form
Metaphase:
- chromosomes line up at the EQUATORIAL PLANE
- spindle fibers attach to chromosomes
Anaphase:
- sister chromatids are separated towards opposite poles
- now, each chromatid has its own centromere
Telophase:
- chromosomes become less condense
- nuclear membrane reforms
- spindle fibers disintegrates
CYTOKINESIS
Chromosomes are made of ____
chromatin
then chromatin is made of DNA
SIGNIFICANCE OF MITOSIS in:
- unicellular
- multicellular
- mode of reproduction
- replace worn-out tissues
Other term for the ff:
- Mitosis
- Meiosis 1
- Meiosis 2
- equational division
- reductional division
- equational division
MEIOSIS 1
Prophase (5)
Metaphase
Anaphase
Telophase
P:
- LEPTONEMA: chromosomes, which are thin and thread-like, begin to condense
- ZYGONEMA: homologous pairs undergo SYNAPSIS to form a BIVALENT (4 chromatids)
- PACHYNEMA: homologous pair intertwine and crosses over @ CHIASMA
- DIPLONEMA: homologous pair separate from intertwining BUT remain attached at chiasma
- DIAKINESIS: homologous pairs are MAXIMALLY condensed
: spindle fibers formed
: nucleus and nuclear membrane disintegrates
M: homologous pairs align at the middle
A: homologous pairs separate towards opposite poles, forming UNIVALENTS (2 chromatids)
T: chromosomes become less condense
: nuclear membrane reforms
: spindle fibers disintegrates
CYTOKINESIS
Does cytokinesis happen for every organisms after MEIOSIS 1?
no
Table of CHROMOSOMES and GENETIC CONTENT
CHROMATIN vs CHROMOSOME
Chromatin
- Interphase
- Loose coils of DNA
Chromosome
- Prophase
- Tightly coiled DNA
What is synapsis?
- pairing and zipping together of homologous chromosomes
- happens in ZYGONEMA
Frequency of CROSSING OVER between Homologous Pairs
- random
- may not happen at all or as many times
at ZYGONEMA, what is FORMED once homologous chromosomes are attached to each other
synaptonemal complex
PLOIDY LEVEL and GENETIC CONTENT keywords
IF:
1. May mother and father chromosome
2. 1 Chromatid per parent
GC: 2C
Diploid
IF:
1. May mother and father chromosome
2. 2 chromatids per parent
GC: 4C
Diploid
IF:
1. Isang parent lang
2. 1 Chromatid sa parent
GC: C
Haploid
IF:
1. Isang parent lang
2. 2 chromatids sa parent
GC: 2C
Haploid
