Genetic Information And Variation Flashcards
totipotent stem cell
Differentiate into any other type of body cell including embryonic cells
Pluripotent stem cell
Can differentiate into any type of body cell (not embryonic)
Found in early embryos
Multipotent stem cell
Can differentiate into some different body cells
Unipotent stem cell
Differentiate into one specific cell
Replication
DNA helices breaks hydrogen bonds
Strands act as template
Nucleotides align via complementary base pairing and attatch with H bonds
Nucleotides align join via phosphodiester bonds and DNA polymerase
Two identical double helixes produced
Transcription
DNA uncoils - hydrogen bonds broken
ONE strand acts as a template
RNA nucleotides align alongside DNA via complementary base pairing
Uracil joins with adenine not thymine
RNA nucleotides join with phosphodiester bonds and RNA polymerase
What is splicing?
Removing introns and joining exons to form mRNA
Why does splicing not occur in prokaryotes
Their DNA doesn’t contain introns
Translation
mRNA binds to ribosome in cytoplasm
tRNA with complementary anticodon binds to mRNA
Ribosomes have two binding sites - for two tRNA
Amino acids from two tRNA attach by peptide bonds
tRNA leaves and fetches another
Polypeptide produced
Interphase
DNA doubles
Organelles replicate
Prophase
Chromosome shortens and thickens ( condensation)
Centrioles more to opposite poles of cell
Nuclear membrane breaks down
Metaphase
Centrioles form spindle
Chromosome moves to equator of spindle and attach via the centromere
Anaphase
Centromere splits
Sister chromatids separate
Sister chromatids pulled to opposite poles of the cell by spindle
Telophase
Chromatids at opposite poles uncoil
Nuclear membrane reforms
Two genetically identical daughter cells produced
Meiosis
Nuclear division that produces four haploid cells
Independent segregation
First meiotic division- homologous chromosomes separate
Chromosomes randomly associate within gamete
Crossing over
Occurs in prophase of meiosis 1
Homologous pairs lie parallel
Chromatids intertwine
Exchange of alleles
New combination produced
Natural selection
Variation due to mutation occurs resulting in new alleles
New allele is beneficial
Organism with beneficial allele more likely to reproduce and survive
Allelic frequency increases
Offspring inherit beneficial allele
