Mod 11: Nucleic Acids

What molecule is all human genetic information encoded?

DNA

Where is DNA found?

nucleus/mitochondria

DNA is organized into what?

distinct chromosomes

How many pairs of chromosomes do humans have?

23 (one copy from each parent)

What is the genetic info in DNA used for?

instructions for the production of proteins at the cellular level

What are somatic cells?

bodily cells other than gametes

What is a diploid?

a somatic cell that contains 2 copies of each chromosome in the genome

What are Germ cells?

sperm and egg

What are germ cells also called?

gametes

What are haploids?

germ cells that contain only one set of chromosomes

What are the nucleic acids polymers of?

nucleotides

What are the 2 nucleic acids?

DNA and RNA

What is the structure of a nucleotide?

1. sugar molecule: ribose and deoxyribose

2. phosphate group

3. nitrogenous base

basic structure of a nucleotide

When is the phosphate group of a nucleotide utilized?

during the polymerization of nucleotides

What is the purpose of the sugar molecule in the nucleotide?

structural backbone

What is the purpose of the nitrogenous base in a nucleotide?

represent the “alphabet” of the genetic code

What is a nucleoside?

a sugar and base without the phosphate (usually just an OH)

What can nucleotides have multiples of?

phosphates - ATP, ADP, AMP

What the bond that keeps polynucleotides together?

phosphodiester bond

How are polynucleotides formed?

phosphodiester bonds form the phosphate group of 5’ carbon and the hydroxl group of 3’ carbon

Why are the 5 and 3 designations important?

DNA and RNA have distinct ends

What the two families of nitrogenous bases?

purines and pyrimidines

Each nitrogenous base tends to…

• pair with a complementary base

• in double stranded DNA and interactions between DNA and RNA

What are the nitrogenous base pairings?

cytosine + guanine (DNA/RNA)

adenine + thymine (DNA)

adeninie + uracil (RNA)

What is the bond of nitrogenous base pairings?

hydrogen bonds

hydrogen bonds between nitrogenous bases

What kind of strands does DNA have?

antiparallel strands

What structure do the two complementary strands in DNA form?

a double helix

How many strands does RNA have?

one

What is the sequence of DNA?

A/T/C/G

What is the sequence of RNA?

A/U/C/G

What is chromatin?

a mixture of DNA and proteins that makes up the chromosomes

What does DNA represent?

the master copy of all the body’s genetic information

What are chromosomes?

DNAs complementary strands of polynucleotides in distinct packages

Where are chromosomes found?

in the DNA

Were are histones found?

in the DNA

What are histones?

proteins that serve structurally for the coiling and packaging of DNA

How long is DNA linearly?

6 feet

Logarithmically, how many base pairs does DNA have?

6×10⁹

What sugar is RNA composed of?

ribose

What does RNA that DNA doesn’t?

uracil instead of thyminet

What does RNA lack?

the continuous helical structure of DNA

What structures does RNA form?

loops and other functional structures

What direction is RNA’s nucleotides?

3’ to 5’

What bond is RNA’s nucleotides held together by?

phosphodiester bonds

How many types of RNA is there?

3

What do all of RNA’s types participate in?

protein synthesis

What is mRNA?

• acts like a set of instructions

• serves as an RNA complimentary copy/transcript of the DNA sequence for translation

When is mRNA generated?

during transcription in the nucleus from a protein coding portion of DNA (a gene)

mRNA copying DNA

What is rRNA (ribosomal RNA)

the primary component of ribosomes

How are ribosomes formed?

from rRNA combing with proteins

What are ribosomes?

read genetic instructions (translation) and assemble proteins by linking amino acids together

What is rRNA considered?

non-coding

ribosomes translating RNA

What is the function of tRNA?

carries an amino acid to ribosomes for incorporation into a polypeptide chain

What does tRNA contain?

an anticodon portion of 3 nucleotides that pair up with mRNA codons

How many tRNA molecules are there?

20 (one for each of the 20 amino acids found in the body)

What shape does tRNA have?

cloverleaf

What is DNA replication?

process where a cell duplicates its genome before dividing, ensures that each daughter cell receives an exact copy of the DNA

What forms along with the double stranded DNA complex?

replication forks or bubbles

What can each strand of the helix serve as?

a template for replication

What happens to the bubbles on DNA strand as replication continues?

bubbles merge until a complete copy of each strand has been produced

What does DNA polymerase do?

add nucleotides to the new strand in a 5’ to 3’ direction (copies the original in a 3’ to 5’ direction)

What do RNA primers do?

start the replication process

what can DNA polymerase only do?

replicate nucleotides continuously in the leading strand

how is the lagging strand synthesized?

discontinuously by joining Okazaki fragments

How long are Ozakazi fragments?

100-200 base pairs long

What joins together Okazaki fragments and the growing strand of DNA?

DNA ligase

When phase is DNA replicated in?

the S phase or synthesis phase

How many genes does mtDNA (mitochondrial) code for?

37 genes in 16.5k base pairsW

What shape is mtDNA?

circular like a plasmid

How can you describe the strands of mtDNA?

heavy and light

How is mtDNA passed to offspring?

via the mother

How is nuclear DNA passed to offspring?

from mother and father

what is mtDNA?

small circular DNA found in the mitochondria

The genes coded from mtDNA code for what?

• structures involved in oxidative phosphorylation (enzymes)

• mRNA and tRNA molecules

What is a gene?

a basic unit of heredity

What does a gene determine?

a specific physical or physiologic trait

What do most genes code for?

a specific protein (or parts of) that have a specific function in the body

What is affected by multiple genes?

physical attributes

How many copies of a gene do offspring inherit?

2

What is an allele?

different versions of the same gene

What are dominant alleles?

determines a trait even if you only inherit 1 copy

What are recessive alleles?

a trait is only expressed when there a 2 copies present

What is Mendelian inheritance?

describes how traits are passed from parents to offspring based on parental genetic makeup

What is a punnet square?

a visual grid to predict the possible genotypes

What disease can help be understood with a punnet square?

cystic fibrosis