Chapter 4, Genetic Control of Cell Function and Inheritance Flashcards
DNA Structure
Double helix. phosphate backbone.
CT- pyrimidine bases, 1 N ring
GA- purine bases, 2 N ring
composed of nucleotides, a phosphoric acid, 5 carbon sugar, and 1 of 4 nitrogenous bases
Packaging of DNA
Autosomes and Sex chromosomes
genes are arranged linearly along each chromosome
small amts of RNA in a tightly coiled structure- chromatin
specfic group of proteins - histones
Function of DNA
genetic coding. each cell contains all DNA, but they differentiate and decide what part they want to use
DNA mutations
Insertion, deletion, duplication, inversion
What types of mutations can be inherited?
any mutation that arises in the germ cells.
most mutations occur in the somatic cells, making them noninheritable
RNA Structure
long string of nucleotides
single stranded
sugar in each nucleotide is a ribose
U replaces T
mRNA
template for protein synthesis.
contains codons- sequence of bases used for transmitting the genetic information needed for protein synthesis
formed from DNA in transcription- DNA bonds are broken so RNA can pair to exposed DNA
rRNA
ribosome is the physical structure in the cytoplasm where protein synthesis takes place
forms a little over half of hte ribosome
produced in nucleolus
tRNA
works to deliver the activated form of an amino acid that is being synthesized to the ribosomes
carries its own specific amino acid to the ribosomes
Transcription
in the cell nucleus. where RNa is synthesized from DNA
complex binds to promoter region (TATA box)
exons: retain protein coding region of the mRNA
introns: between the cells
: permits different proteins to be expressed from a single gene and reduces how much DNA must be contained in their genome
Translation
the synthesis of of a protein using the mRNA template
Gene Expression Regulation
:degree to which a gene or particular group of genes is active
Transcription factors:
•Induction: an important process by which gene expression is increased
•Gene repression: process by which a regulatory gene acts to reduce or prevent gene expression
•Only about 2% of the genome encodes instructions for the synthesis of proteins; the remainder consists of noncoding regions that are structural or serve to determine where, when, and in what quantity proteins are made. The degree to which a gene or particular group of genes are actively being transcribed is called gene expression. A phenomenon termed induction is an important process by which gene expression is increased
Genes controlling protein synthesis
- Structural Genes: specify the amino acid acid sequence of a polypeptide chain
- Regulator Genes: serve a regulatory function without stipulating the structure of protein molecules
- Cells decode mRNAs by reading their nucleotides in groups of three, called codons. Here are some features of codons:
- Most codons specify an amino acid
- Three “stop” codons mark the end of a protein
- One “start” codon, AUG, marks the beginning of a protein and also encodes the amino acid methionine
- Codons in an mRNA are read during translation, beginning with a start codon and continuing until a stop codon is reached. mRNA codons are read from 5’ to 3’ , and they specify the order of amino acids in a protein from N-terminus (methionine) to C-terminus.
Barr Body condensation
when 2 x chromosomes cant compete with one another, and when stem cells come out to become the 3 derms (meso, endo, ecto) they can decide which x that they want to use, and the second x becomes the barr body
Mitosis
replication of DNA to duplicate somatic cells. typical cell cycle. I - begins to prepare, dna is replicated
P - spindle fibers, chromatides, centrometes form
M - everything lines up in the middle
A - it cleaves
T - new nuclear envelope
