Module 3 Flashcards
1
Q
What is DNA
A
- made up of a sequence of smaller components called nucleotides
- 4 different nucleotides that our bodies use to make DNA: Adenine, Thymine, Guanine, Cytosine
- DNA is 2 strands of nucleotides wound together
- all instructions to build all living things on earth is spelled out with 4 letters
2
Q
Structure of DNA
A
- nucleotides bind 2 strands of DNA together according to “Base pair rules”
- a always binds T
- C always binds G
3
Q
How DNA holds instructions for life
A
- sequence of nucleotides in DNA determines sequence of amino acids in a protein
- sequence of amino acids in a protein determines shape and function of protein
- your genome (all your genes) are composed of about 3 billion nucleotide pairs
4
Q
Chromosomes
A
- all DNA found in 46 chromosomes in each cell nucleus
- chromosomes are long strands of DNA tightly wound up
- gene is a section of DNA that holds instructions for how to build one protein or a part of a protein
- each chromosome contains 100s to 1000s of genes
5
Q
Making Proteins - 2 challenges
A
- DNA is in the nucleus, but we need proteins in the cytoplasm: messenger to transport info from DNA to where protein is assembled, this messenger is called mRNA, mRNA is produced in a process called transcription
- DNA is made of nucleotides, but proteins are made of amino acids: mRNA is used as a template to build a protein, this process is called translation
6
Q
Protein synthesis- 2 steps
A
- Transcription: DNA –> mRNA; in the nucleus
- Translation: mRNA –> protein; in the cytoplasm
7
Q
Transcription
A
- base pair rule used to build mRNA A-T (U) G-C
- mRNA is a single strand of nucleotides. uses a nucleotide called uracil wherever DNA would have thymine
- during transcription, making a copy (transcribing) of one strand of DNA- this copy is mRNA and will serve as a template to build protein
8
Q
Translation- assembling the protein
A
- mRNA serves as a template to direct assembly of protein- holds instructions on which amino acid comes next
- sequence of nucleotides in mRNA is “translated” into sequence of amino acids
- mRNA is read in sequences of 3 nucleotides that correspond to different amino acids (genetic code)
9
Q
Translation
A
- mRNA is read in sequences of 3 nucleotides, called codons
- codons are specific for an amino acid
- go from a language of 4 letters (nucleotides) to a language of 20 (amino acids(
- called genetic code
- all living things use the same code
10
Q
Protein Synthesis Summary
A
- transcription in nucleus results in production of RNA from DNA
- translation at ribosomes results in production of proteins
11
Q
Gene Expression
A
- when a gene is expressed it is turned on and is transcribed and translated into a protein
- when a gene is not being expressed it is turned off and is not transcribed and translated into a protein
- different cells will have different genes turned on and off at different times
12
Q
Cell Cycle
A
- ordered sequence of events in lifetime of cell
- tightly regulated by many different genes: cell division only occurs when necessary to replace cells or for growth; cell division stops when we have enough cells
1. interphase- 90% of time; normal cell functions
2. mitotic phase- 10% of the time; active cell division
13
Q
Point mutations
A
- occur at a single point
- can have varying effects
14
Q
Frameshift mutations
A
- due to the addition or deletion of a nucleotide
- often result in different or defective proteins, it affects where the reading of the sequence of codons start
- silent mutation
- missense
- nonsense
15
Q
Proto-oncogenes
A
normal genes that control cell cycle
ex. tumor suppressor genes, growth factors, transcription factors
