Chromosomes And Meiosis Flashcards
Chromosomes
Long, thread-like structures that form part of the chromatin network in the nuclei of cells
- can be stained easily
Somatic cells
Body cells
Homologous pair
Matching maternal and paternal chromosomes (same size, shape and coding genes in place)
Chromatids
2 identical threads formed during chromosome replication
Diploid
2n
Cells containing full number of chromosome (e.g. 46 in humans)
Allele
One or two more forms of a gene
- a contrasting form of a gene for the same characteristic
Meiosis
Cell division that takes place in reproductive organs of both plants and animals to produce gametes (sex cells) in animals and spores in plants
Haploid
n
Cells that have half the number of chromosomes
Gene
A short length of DNA which controls and organisms characteristic
- sections of chromosome that code for specific characteristics
Morula
Basic mass of replicated cells which form basic embryo
Microsporangia
Pollen sacs in the male anthers (part of stamen)
Mega sporangia
Ovules in the female ovaries
Meiosis 1
Reduction division
- results in two cells being formed- each with a haploid (n) number
Meiosis 2
Copying division
- involves two haploid cells replicating to form 4 haploid cells
Chiasma
Point of contact and where breakage occurs between two chromatids
Synapsis
Process in which replicated homologous pairs come together to form bivalents
Bivalent
Chromosomes which lie next to each other
Tetrad
2 chromosomes that make up a homologous pair
Genome
All the genes in an organism
Chromosomal non-disjunction
Occurs when chromosomes fail to separate correctly during Anaphase 1 of meiosis
Aneuploidy
Condition resulting from fertilization involving abnormal gametes which result in a zygote with an extra/ missing chromosome
Syndrome
Physical/ mental characteristics affected individuals suffer from
Diagnosis
Identifying the nature of an event
Prognosis
Predicting how the event will develop
Amniocentesis
Process whereby a small sample of fluid is removed from the amniotic cavity in the uterus
Polyploidy
A condition where there are more than two sets of chromosomes in a cell.
Occurs more commonly in plants
Occurs as a result of abnormal mitosis where a full set of chromosomes does not separate during Anaphase 1
Total non-disjunction
The phenomenon there a full set of chromosomes does not separate during meiosis
Autosome
The normal chromosomes not involved in sex determination
Gonosome
The sex chromosomes that determine the gender of an individual
Karyotype
The complete number of chromosomes in a diploid cell, arranged in Paris according to size, shape and number
