Lecture 17 Flashcards
(meiosis) cell division in which one … germ cell produces four … daughter cells
diploid; haploid
(meiosis) prophase I in an organism in which 2n = 4
dipolid cell has two … of each chromosome. nuclear envelope … and … develop. homologs pair up to form …, … takes place and … become visible
homologues; breaks down; spindles; tetrads; crossing over; spindles
crossing over occurs between … of a … homologous pair. it can increase …
non-sister chromatids; synapsed; genetic variation
(meiosis) metaphase I:
… line up at the … … are visible
tetrads; metaphase plate; spindles
(meiosis) anaphase I: the attachments between the homologous chromosomes … and … pull the chromosomes towards the poles
breaks down; kinetochores
(meiosis) telophase I and cytokinesis:
chromosomes reach the poles, the … breaks down and … reform. Cytokinesis produces … daughter cells
spindle; nuclear envelopes; two
(meiosis) prophase II:
the nuclear envelope .. and the spindles …
breaks down; reform
(meiosis) metaphase II:
… line up on the …
sister chromatids; metaphase plate
(meiosis) anaphase II: the centromeres that bind the sister chromatids together are …, enabling each chromatid to …
broken down; move to opposite poles
(meiosis) telophase II and cytokinesis:
… chromosomes reach the poles, the … breaks down and … reform. Cytokinesis produces .. daughter cells (..) from the original single cell (…)
unduplicated; spindle; nuclear envelopes; four haploid; n=2; 2n=4
(mitosis vs. meiosis)
prophase: in mitosis, … are present, in meisos I, … is formed by .. of ..
duplicated chromosome; tetrad; synapsis; homologous chromosomes
(mitosis vs. meiosis) metaphase-
mitosis: … positioned at the metaphase plate
meiosis I: … positioned at the plate
chromosomes; tetrades
(mitosis vs. meiosis) anaphase/telophase: mitosis: ... separate during anaphase meiosis I: ... separate mitosis 2: ... separate
sister chromatids; homologues; sister chromatids
… separate during meiosis.
alleles
mitosis is a process required for … and … of the organism
meiosis is a process required for the … of an organism
growth; development; sexual reproduction
inheritance of characteristics is achieved during the process of
reproduction
two factors determine characters:
- ….
- … during …
heredity; modification; development
the inherited preformed or predetermined genetic program provides information about what is possible, but regulation of genetic expression involves … It is the latter that is …
interpretation; epigenetic
epigenetics is a … process that affects the … of genes
reversible; expression
the epigenome is responsible for: ... distinct ... in mammals ... gene expression in genomic imprinting ... inactivation ... silencing of transposons
200; cell types; mono-allelic; X chromosome; transcriptional
epigenetic factors:
DNA …
.. modification (…, …)
non-coding .. molecules
methylation; histone; acetylation; methylation; RNA
methylation of DNA and histones causes nucleosomes to … transcription factors cannot … and genes are not …
pack tightly together; bind the DNA; expressed
histone acetylation results in … of nucleosomes. transcription factors can bind the DNA and genes are …
loose packing; expressed
methylation = ... of genes acetylation = genes are ...
reduced expression; available to be expressed
epigenetic changes to the chromatin may result from:
…
…
…/…
…
…
and may result in: …, … disease, … disorders, …
development; environmental chemicals; drugs/pharmaceuticals; aging; diet; cancer; autoimmune; mental; diabetes
epigenetics plays a role in the … of gene expression
control
cancer cells have a … level of methylation (… DNA) than healthy cells. Too little methylation causes:
- activation of genes that …
- chromosome …: highly active DNA is more likely to be …, … and …
- loss of …
lower; more active; promote cell growth; instability; duplicated; deleted; moved to other locations; imprinting
cancer cells can also have genes that have … methyl (are … active) than nomral. the types of genes that are turned down in cancer cells:
- keep cell growth ..
- repair …
- initiate …
more; less; in check; damaged DNA; programmed cell death
DNA methylation occurs in
CpG islands
- before replication, DNA is fully … at … dinucleotides
- During replication, new DNA strands are synthesized without …
- after replication, each new DNA molecule will have … on one strand but not the other: the DNA is …
- methyl groups attract … enzymes, which add methyl groups to the … strand
- resulting in fully .. DNA
methylated; CpG; methyl groups; methylation; hemimethylated; methyltransferase; unmethylated; methylated
histone modificates are … to daughter cells. new histones are synthesized in … during the cell cycle. the modifications on histones happen after … have formed
not passed on; G1; nucleosomes
the genome dynamically responds to the environment: …, …, …, … and other factors activate chemical switches that regulate gene expression
stress; diet; behavior; toxins
the epigenome changes in response to …, which come from … the cell, from …, or from the …
signals; inside; neighboring cells; outside world
… can also directly affect the “epigenetic state” of DNA
… from it are turned into … groups
food; nutrients; methyl
dificiency of methyl-donating folate or choline during late fetal or early postnatal development causes certain regions of the genome to be … for life
under-methylated
a mother’s … influences the epigenome of her offspring
diet
… influences gene expression
dietary methyl
