Chapter 4 Flashcards
(23 cards)
What is the nucleus the site of?
DNA replication
RNA synthesis
RNA processing
Ribosome assembly
What does the nuclear envelope or membrane contain?
Two phospholipid bilayers- outer membrane is continuous with endoplasmic reticulum, inner membrane has proteins that bind the nuclear lamina Nuclear lamina (protein framework)- mesh that provides structural support, consists of fiborous proteins called lamins Nuclear pores
Slides 6-9
What is genotype and phenotype?
Genotype- genetic composition of an organism (RR)
Phenotype- physical appearance of an organism (red trait)
How does the number of linkage groups relate to the number of chromosomes?
Number of linkage groups=number of chromosomes
Phenotypic traits are inherited together as linkage groups
What is replication, transcription, and translation in DNA synthesis?
Guaranteed test questions on this
Replication- duplicate copy of DNA molecule made by DNA polymerase
Transcription- synthesis of RNA molecule from a DNA template by RNA polymerase
RNA synthesis using DNA template
Nucleotide->nucleotide
Translation- synthesis of polypeptide chain from an mRNA template (ribosomes)
Protein synthesis using mRNA template
Nucleotide->amino acid
What are mRNAs, rRNAs, and tRNAs?
mRNA- molecules that serve as templates for protein synthesis
rRNA- component of ribosomes
tRNA- adaptor molecules that align amino acids along the mRNA template
What is the genetic code?
Corresponding information from nucleotide triplets called codons that encode individual amino acids in proteins
Codons are the basic units of the genetic code
Picture on slide 20
What is a general TREND between organism complexity and genome size?
It often happens that increased genome complexity=increased genome size
What is a gene?
A segment of DNA within a chromosome that is expressed to yield a functional product
Genes make up a small proportion of the entire genome
Slide 29
What are exons, introns, and RNA splicing?
Exons are segments of protein-coding sequence
Introns are segments of nonprotein coding sequences, they make up the majority of a genes RNA coding region
RNA splicing is the joining of exons in a precursor mRNA molecule
Slide 24
How does the size of eukaryotic organism affect the number of genes, protein coding sequence, intron sequence, and introns per gene?
If size goes up Number of genes go up Protein coding sequence percentage goes down Intron sequence percentage goes up Introns per gene go up
What is the other 60-70% of the human genome that is not a typical gene?
Several types of highly repeating sequences that make up a significant portion of the remainder of the genome
Many of these have been found to encode regulatory RNAs that play important roles in regulation of other genes (micro RNAs and long non-coding RNA’s) or stability and replication of chromosomes
What is the simplest present day prokaryote?
Mycoplasma genitalium
Second smallest genome of known cells
Minimal gene set required to maintain self replicating organism
What is he major question about phenotypic complexity and genetic complexity?
How phenotypic complexity is generated since it does not rely solely on increased genetic complexity
What is the human genome?
Distributed on 24 different chromosomes
22 autosomes, X and Y sex chromosomes
Human genome consists of approx 21000 genes and contain more intron sequence than genes in smaller animals
What is chromatin?
Eukaryotic chromosomal DNA complexes with proteins
Typically about twice as much protein as DNA
Is chromosome number related to complexity in the animal?
NO
What are nucleosomes and histones?
Nucleosomes are the basic structural units of chromatin
They consist of DNA+histones
Chromatosome is 166 basepairs plus histone H1
Histones are small proteins containing high proportion of the basic amino acids arginine and lysine. This facilitated binding to the negatively charged DNA sugar phosphate backbone
H1, H2A, H2B, H3, H4
Slide 41-43
What are euchromatin and heterochromatin?
Euchromatin- decondensed-transcriptionally active interphase chromatin
Heterochromatin- highly condensed, transcriptionally inactive chromatin, contains highly repeated DNA sequences (Arrowheads on TEM)
Slide 45
What are the two types of heterochromatin?
Constitutive heterochromatin- contains DNA that is not transcribed in any cell type
DNA sequences at centromeres
Facultative heterochromatin- contains DNA sequences that are not transcribed in the cell being examined but may be transcribed in other cell types
How is the DNA organized in metaphase chromosomes?
Organized into large loops attached to a protein scaffold
What is a centromere and a kinetochore?
Centromere- region of chromosome that plays a critical role in editing the correct distribution of duplicated chromosomes to daughter cells during mitosis
Contains a histone known as centromeric histone H3
Kinetochore- a protein structure associated with the centromere where microtubules bind
Slide 49
What are telomeres?
Sequences at the ends of eukaryotic chromosomes
Role in maintaining stability of linear chromosomes
Maintained by unique enzyme known as telomerase
Slide 53 structure
