DNA & Chromosomes (Lec 1) Flashcards
What are genes?
the information containing elements that determine the characteristics of a species
What does it mean for DNA strands to be antiparallel?
each strand’s sequence is complementary to partner
What are the two purines?
adenine and guanine
note: purines = small name, big ring
Name the base pairs
Adenine pairs with Thymine (2 H bonds)
Guanine pairs with cytosine (3 H bonds)
What are the two pyrimidines?
Cytosine and Thymine
True or False?
At replication, the entire genome must be duplicated and passed to the daughter cell.
True
Discovery of the structure of DNA provided a mechanism for this to occur….
complimentary strands allow the genome to be replicated
each strand serves as the template
How many different chromosomes is the human genome distributed over?
24
What is a chromosome?
a single long linear DNA molecule associated with proteins that fold and pack it into a compact structure
Each human cell contains 2 copies of each chromosome except…
germ cells and RBCs
How many pairs of autosomes and sex chromosomes are there?
22 pairs of autosomes
2 sex chromosomes
Does interspersed DNA contain genes?
no
How do you know if a DNA sequence is functional or nonfunctional?
functional sequences are conserved during evolution
nonfunctional sequences mutate randomly without consequence
What happens in interphase?
chromosomes are replicated; they are decondensed and can’t be easily distinguished
What happens to chromosomes in mitosis?
become highly condensed and separated into two daughter nuclei
What does a centromere do?
allows one copy of each duplicated and condensed chromosome to be pulled into each daughter cell when the cell divides
What are telomeres?
at the ends of a chromosome, contain repetitive sequences that enable the ends to be efficiently replicated
Protein + nuclear DNA = ?
chromatin
What are the DNA binding proteins involved in forming chromosomes?
histones and non-histone chromosomal proteins
What are nucleosomes?
most basic unit of chromosome packing
Each individual nucleosome core particle consists of how many histone proteins?
8
What is linker DNA produced?
DNA that is broken down by cutting between nuclesomes and degrading the exposed DNA between nucleosome and core particles
Nucleosome particle is disc-shaped with DNA wrapped ____ turns
1.7
How is DNA packaged?
interactions between DNA and histone (142 H bonds are formed between DNA and the histone core in each nucleosome)
True or False?
Histones are highly conserved; most changes would be lethal
ture
What do chromatin remodeling complexes do?
allow further loosening of DNA/histone contact
Chromatin remodeling proteins are related to helicases and are ___ depending
ATP
What is Histone H1?
linker histone, larger than others, less conserved, contacts both DNA and protein, changes the path of the DNA as it exits the nucleosome
