Genetics and Cell Reproduction

Classes of gene mutations

Substitution

deletion

addition

Substitution

one DNA nucleotide is replaced by another to it codes for the wrong amino acid

Deletion

one nucleotide is missing or removed causing every codon afterward to be wrong

Addition

nucleotides are added causing every codon afterward to be wrong

Functions of DNA

Hereditary (Genetic) Material – Passed from generation to generation

Protein Synthesis - Nucleic acids are the blueprints for building (synthesizing) proteins

How is DNA structured

Made of nucleotides (monomers) Each nucleotide contains a sugar, a phosphate, and a nitrogenous base.

DNA backbones

The phosphates and sugars connect to each other to make up the backbone of a DNA strand. The phosphate side is called the 5’ end. The sugar side is called the 3’ end.

Why is DNA double stranded

Two strands are antiparallel

Joined by hydrogen bonds between nitrogenous bases

DNA bases

A always goes with T

C always goes with G

Central Dogma

How do genes influence proteins

Determines the amino acid sequence of a protein

Transcription

the process where a gene's DNA sequence is copied into a messenger RNA (mRNA) molecule by the enzyme to leave the nucleus

Same bases in OPPOSITE orders

Translation

the process where the genetic code from messenger RNA (mRNA) is read by ribosomes to build specific proteins

Occurs in the CYTOPLASM

3 Baes in a codon

DNA replication

Semi conservative process

Consists of one new strand and one old strand

Steps of replication

1. DNA “unzips”

2. Each “open” nucleotide binds to a new complementary nucleotide.

3. End result is two identical strands of DNA.

How does replication start

DNA unwinds and an enzyme called helicase breaks down the hydrogen bonds holding the base together

ASE = Enzyme

How are new strands built

Elongation

RNA primer binds to the template strand to provide a starting point

DNA polymerase extend the new strands by adding one nucleotide at a time

How does replication end

Termination'

Once the template strand has been copied DNA ligase fix any breaks in the chains and put the strands back together

2 new DNA double helices

What is a mutation

a change in the genetic material in an organism

often an error in DNA replication

Negative impacts of mutations

most diseases are linked to recessive genes

chromosomal mutations or gene mutations

Mutagens

Sickle cell anemia

Phenylketonuria

Tay Sachs

Cystic Fibrosis

Why is DNA replication necessary

Cells need a second copy of DNA before they can duplicate

Epigenetics

The impact of environment on genetics

Epigenetics are SOMETIMES inherited

DNA methylation

An epigenetic mutation where a cytosine base becomes methylated through the action of an enzyme.

What are chromosomes

Condensed strands of DNA and proteins organized

Structure of chromosomes

Nucleosome- DNA wrapped around histones

Chromatin- A long strand of nucleosomes

Chromosome- a condensed bundle of chromatin

Why are chromosomes necessary

They help protect DNA and reduces the amount of mutations

What does chromatin consist of

a mixture of proteins (Histones) and DNA

How do chromosomes form

Chromatin condenses (Packages) by wrapping and coiling itself to form a chromosome

How do epigenetic changes work

They tag DNA which activates or represses gene expression

How does DNA methylation change the DNA

They do not change the dna sequence

rRNA

makes ribosomes