BIOL 121 Flashcards
(35 cards)
What is DNA?
DNA is a double stranded molecule shaped like a spiral ladder
What are genes?
Genes are small sections of DNA that code for a specific protein
What does the Human Genome Project estimate?
- humans have 20-25k protein coding genes
- ranges in size from a few hundred to over 2 million
What is a phenotype?
- observable physical properties of an organism
- physiological, morphological, behavioural
What are alleles? What are they responsible for?
- Alleles are different versions of the same genes
- they are responsible for variation in inherited traits
Alleles rise due to what?
Mutations in the DNA
What is a mutation?
A change in the sequence of nucleotides in the DNA
A mutation may be as small as …
a change in one nucleotide/step
Types of mutation include:
- substitution
- insertion
- deletion
How can mutation be caused?
- due to mistakes when DNA is replicating
- environmental factors that damage DNA (UV)
Explain why white black bears exist
- single nucleotide substitution of Adenine for Guanine in the mc1r gene
- protein produced by this new allele was non-functional
- resulted in white instead of black fur
What is sickle cell disease caused by?
A SNiP in the beta-globin gene
Explain the sickle cell disease (mutation and outcome)
- 6th amino acid is valine instead of glutamic acid, affecting the shape (function) of Hb
- results in red blood cells turning sickle-shaped
- negative effects on oxygen carrying capacity
What is DNA packaged into?
Chromosomes
Where are chromosomes located in?
- nucleus of somatic cells
- gametes
What are somatic cells? Give examples.
- all cells int he body that aren’t sperm and egg cells
- examples include cells of internal organs, skin, bones, blood, connective tissue …
What are gametes? How are they produced?
- reproductive cells produced by sexually reproducing organisms
- produced via meiosis
How many chromosomes are in a human somatic cell?
- typically 46 total chromosomes
Human somatic cells typically have how many pairs of chromosomes?
- 23 total pairs
- 22 pairs of autosomes
- 1 pair of sex chromosomes
Why do you have 23 pairs of chromosomes?
- you inherit one set of 23 chromosomes from your mom
- you inherit one set of 23 chromosomes from your dad
- in total you have 46 chromosomes OR 23 pairs
What are homologous chromosomes?
Homologous chromosomes are a matched pair of chromosomes
What do homologs have in common? Differ?
- they are the same size and have the exact same centromere location
- they carry the same sequence of genes
- may carry different alleles
What is a centromere?
- the constriction point on a chromosome, which divides into two arms
What is a locus?
A specific location on a specific chromosome
