Topic 3A Flashcards
(26 cards)
what is a pluripotent stem cell
a type of stem cell which can differentiate into any type of cell in the body
what is a totipotent stem cell
a type of stem cell which can differentiate into any type of cell in the body or into cells which make up extra-embryonic tissues like the placenta
what is a gene expression
the synthesis of active functional products through the transcription and translation of a gene.
what is pre-mRNA
the direct products of transcription before splicing occurs.
How is pre-mRNA converted to mature mRNA
Post-transcription modifications and splicing alter structure of the mRNA molecule to remove introns.
what is mature mRNA
the product of splicing which includes only exons. this is used in translation to produce functional polypeptides
what are epigenetic modifactions
Modification which cause changes in gene expression that are not due to alterations in the nucleotide base sequence of DNA
what are histones
proteins which help to package DNA tightly in the form of chromatin. The DNA coils around the histone proteins
types of epigenetic modifications
DNA methylation, Histone acetylation: the addition of acetyl groups to histone proteins which make them bind less tightly to DNA molecules and hence allow for increased transcription.
What is polygenic inheritance
The control of a trait by multiple genes
what is a gene linkage
the phenomenon seen where genes with similar loci re typically inherited together,mdince they are unlikely to be separated during mitosis.
what is autosomal linkage
Autosomal linkage is the inheritance of genes with similar loci on non-sex chromosomes together
what are chiasmata ( during meiosis )
the points where homologous chromosomes cross over in meiosis
what’s cross-pollination
a type of pollination in which pollen is transferred from an anther of one plant to a stigma of a different plant.
how do the male nuclei reach the embryo sac
pollen grain from one plant lands on the stigma of another plants, then
mitosis of pollen grain to form a pollen tube nucleus and 2 male gametes, then
pollen tube grows from the grain down to the ovule via the digestion of the style, then
pollen tube delivers 2 male gametes
what is micropyle ( idk if memorize just understand )
pore in the integumentary of an ovule through which the pollen tube enters the embryo sac, remain as a pore in the testa
what are epigenetics
the study of changes of gene expression due to the envrioment, witout changing tehe sequence of the DNA, but by the addtion of chemical groups that effect transcription.
methylation of DNA
adding a methyl group to cytosine or guanine to make it harder for RNA polymerase to join, so transcription is inhibited
