Lecture 20: Genetics and Plant Breeding - 11/18 Flashcards
Nucleus
A structure that contains a cell’s genetic information
How is DNA stored (how many nucleotides in each group)?
DNA is stored as a linear sequence in groups of 3
What are the 4 base pairs?
Adenine (A), guanine (G), cytosine (C), guanine (G)
Uracil (U)
Uracil
Replaces thymine in RNA
How are nucleotide bases paired?
A is paired with T (or U in RNA)
G is paired with C
Which pentose sugars do DNA and RNA have?
DNA has deoxuyribose
RNA has ribose
Chromosomes
In the nucleus, subgroups of DNA that are tightly packed with histones (proteins)
Diploid
Has two pairs of chromosomes
What regions is the DNA sequence made up of?
It is made up of genes and intergenic regions (regions in between genes)
Exons
Portions of the gene that will be transcribed to mRNA and then to protein
Introns
Portions of the gene that will not be translated (will be spliced out)
Central dogma
Information flows from DNA–>RNA–>protein
What is the process of turning DNA to RNA called?
Transcription
What is the process of turning RNA to protein called?
Translation
Where is mRNA synthesized?
The nucleus
Once mRNA has been synthesized, where does it travel?
It exits the nucleus through its nuclear pores, where translation then occurs on ribosomes in the cytoplasm or rough ER (endoplasmic reticulum)
What are the three types of RNA?
mRNA, rRNA, tRNA
mRNA
Messenger RNA. Contains the codon (3 pase pair) information to build a protein
rRNA
Ribosomal RNA. Assembles with ribosomal proteins to form the ribosome, which is where mRNA is read and translated to protein form
tRNA
Transfer RNA. Carries amino acids to ribosomes to make proteins. Has an anticodon, which is the matching base pairs to the codon
An example of an anticodon for AUG is UAC because A matches with U, U matches with A, and G matches with C
Mitosis - # of chromosome duplications and nuclear/cellular divisions
One chromosome duplication
One nuclear/cellular division
Meiosis - # of chromosome duplications and nuclear/cellular divisions
One chromosome duplication
Two nuclear/cellular divisions
What is the difference between genotype and phenotype?
Genotype is the genetic makeup of an organism, whereas phenotype is its appearance/traits
How might genotype and phenotype for plants be similar yet different?
It’s possible for genotypically different plants to look phenotypically similar, and phenotypically different plants to be genotypically similar
Allele
A version of a gene. Diploid organisms have two alleles for one gene
Homozygous
Possessing two alleles of the same type
Heterozygous
Possessing two alleles of different types
How can phenotype be deceiving in regards to genotype?
A homozygous and heterozygous genotype can produce the same phenotype
Is there complete independent assortment of genes? Why or why not?
No, because genes reside on chromosomes, which are rearranged during meiosis (not the genes themselves)
Crossing over
In meiosis, when two homologous chromosomes cross over at a chiasma, exchanging genetic information
Linked genes
When two genes are on the same chromosome
Mutations
Changes in DNA sequence, which are normally harmful (but occasionally beneficial)
Do all mutations result in a change?
No, because there is some redundancy in the genetic code; multiple combinations of nucleotides code for the same amino acid, so sometimes a mutation will still produce the same amino acid, producing no change
