F14 Flashcards
Essential concepts
- Life depends on the stable storage, maintenance, and inheritance of genetic information.
- Genetic information is carried by very long DNA molecules and is encoded in the linear sequence of four nucleotides: A, T, G, and C.
- Each molecule of DNA is a double helix composed of a pair of antiparallel, complementary DNA strands, which are held together by hydrogen bonds between G-C and A-T base pairs.
- The genetic material of a eukaryotic cell—its genome—is contained in a set of chromosomes, each formed from a single, enormously long DNA molecule that contains many genes.
- When a gene is expressed, part of its nucleotide sequence is transcribed into RNA molecules, most of which are translated to produce a protein.
- The DNA that forms each eukaryotic chromosome contains, in addition to genes, many replication origins, one centromere, and two telomeres. These special DNA sequences ensure that, before cell division, each chromosome can be duplicated efficiently, and that the resulting daughter chromosomes can be parceled out equally to the two daughter cells.
- In eukaryotic chromosomes, the DNA is tightly folded by binding to a set of histone and nonhistone chromosomal proteins. This complex of DNA and protein is called chromatin.
- Histones pack the DNA into a repeating array of DNA–protein particles called nucleosomes, which further fold up into even more compact chromatin structures.
- A cell can regulate its chromatin structure—temporarily decondensing or condensing particular regions of its chromosomes—using chromatin-remodeling complexes and enzymes that covalently modify histone tails in various ways.
- The loosening of chromatin to a more decondensed state allows proteins involved in gene expression, DNA replication, and DNA repair to gain access to the necessary DNA sequences.
- Some forms of chromatin have a pattern of histone tail modification that causes the DNA to become so highly condensed that its genes cannot be expressed to produce RNA; a high degree of condensation occurs on all chromosomes during mitosis and in the heterochromatin of interphase chromosomes.
Show how A typical duplicated mitotic chromosome is highly compact
Show how Abnormal chromosomes are associated with some inherited genetic disorders
Show how Adenosine triphosphate (ATP) is a crucially important energy carrier in cells
Show how All amino acids have an amino group a carboxyl group, and a side chain (R) attached to their alpha carbon atom
Show how Amino acids in a protein are held together by peptide bonds.
Show how ATP is synthesized from ADP and inorganic phosphate, and it releases energy when it is hydrolyzed back to ADP and inorganic phosphate
Explain bases
Show how Chromatin-remodeling complexes locally reposition the DNA wrapped around nucleosomes
Show how DNA is made of four nucleotide building blocks
Show how DNA packing occurs on several levels in chromosomes
Show how Griffith showed that heat-killed infectious bacteria can transform harmless live bacteria into pathogens
Show how Hershey and Chase showed definitively that genes are made of DNA
Show how Heterochromatin specific histone modifications allow heterochromatin to form and to spread.
Show how In many eukaryotes, genes include an ecess of interspersed, noncoding DNA
Show how Interphase chromosomes occupy their own distinct territories within the nucleus.
Show how Macromolecules are abundant in cells
Show how Most genes contain information to make proteins
Show how Nucleosomes contain DNA wrapped around a protein core of eight histone molecules
Show how One of the two X chromosomes is inactivated in the cells of mammalian females by heterochromatin formation
Show how The chromatin in human chromosomes is folded into looped domains
Show how The duplication and segregation of chromosomes occurs through an ordered cell cycle in proliferating cells
Show how The nucleolus is the most prominent structure in the interphase nucleus
Show how the nucleotide subunits within a DNA strand are held togehter by phosphodiester bonds
show how The pattern of modification of histone tails can determine how a stretch of chromatin is handled by the cell.
Show how The strucutre of the nucleosome core particle, as determined by x-raw diffraction analysis, receals how DNA is tightly wrapped around a disc-shaped histone octamer.
Show how The struggle of chromatin varies a single interphase chromosome
Show how The two strands of the DNA double helix are held together by hydrogen bonds between complementary base pairs
Show how Three DNA sequence elements are needed to produce a eukaryotic chromosome that can be duplicated and then segregated at mitosis
Describe how Changes in nucleosome structure allow access to DNA
What is the difference between phosphoanhydride bonds and phosphodiester bonds
There are three phosphoryl groups; alpha(α), beta(β), and gama(γ) esterified to the C-5 hydroxyl group of the ribose. The linkage between ribose and the α-phosphoryl group is a phosphoester linkage because it includes a carbon and a phosphorus atom, whereas, the β- and γ-phosphoryl groups in ATP are connected by phosphoanhydride linkages that don’t involve carbon atoms. All Phosphoanhydride have considerable chemical potential energy, and ATP is no exception.
