the building blocks within DNA
nucleotide
example of a nucleotide
ATP
long polymer/molecule made up of a sequence of nucleotides
DNA
specific segment of DNA that determines a particular protein
gene
List the nucleotide bases for proteins for DNA:
Adenine
Guanine
Cytosine
Thymine
List the nucleotide bases for proteins for RNA:
Adenine
Guanine
Cytosine
Uracil
What happens in the “transcription” process?
DNA is transcribing to RNA. The RNA is a singl stranded “copy”.
RNA carries information out of nucleus to a ribosome, where it is translated to make a ________
protein
What is the 3 base code when translating?
For every three nucleotides determines a particular amino acid. Language is called codons
Long sequences of amino acid chains form ______
proteins
When a DNA is essentially loose, not condensed down.
chromatin
During DNA synthesis, chromatin is replicated producing what?
sister chromatids
Sister chromatids are joined by a _________
centromere
Attachment point for spindle fibers that pull chromatids apart during cell division
centromere
Individual strands of DNA
chromosomes
How many chromosomes are in a human cell? How many pairs?
46; 23
Why do cells divide?
- Development and growth
- Replacement and repair
- Sex
single cell formed by union of sperm and egg
zygote
cell division that results in identical (daughter) cells
mitosis
Two main phases of the cell cycle:
- Interphase
2. M-phase
when the cell pinches off and turns into 2 new daughter cells
cytokinesis
List the phases of Mitosis:
Prophase Metaphase Anaphase Telophase Cytokinesis
What is the product of mitosis?
two genetically identical daughter cells
a pair of chromosomes that carry the same genes, but potential different versions (alleles)
homologous pairs
identical, attached copy of a chromosome
sister chromatids
different versions (forms) of a specific gene
alleles
One copy from maternal and one copy from paternal source
What can different alleles produce?
May produce the same resulting protein or different forms of a protein and different physical characteristics
Cells that have half the number of chromosomes
haploid
What is the purpose of meiosis?
Sex and to produce genetically different cells - male or female gametes
If two sematic (non-sex) cells came together to form a new individual, how many chromosomes would that zygote have?
92
meiosis selectively reduces the number of chromosomes in gametes by half
selective reduction
to increase genetic diversity in offspring
genetic recombination
Meiosis is a lot like Mitosis, but what’s the difference?
Meiosis has two cell divisions
Exchange of genetic information between non-sister chromatids
crossing-over
when does crossing over occur?
when homologous chromosomes pair with one another
nondisjunction
Not come together, do not come apart
Imbalance in chromosome number causes abnormalities in development
most result in miscarriage
What causes down syndrome?
an extra chromosome 21
List characteristics of down syndrome:
• Limits in mental development
• Abnormal skeletal growth – short stature and body parts
• Unique facial features – flatten nose, protruding tongue that forces mouth open to cause speech impediment, folded skin at corner of eyes
• Heart and digestive defects are common
• Risk of down syndrome increases with mother’s age rapidly after age 35
o By age 45 the mother is 45X more likely than at age 20
Human chromosomes have how many genes?
~20,000-25,000
Segment of DNA that codes for a particular protein
gene
Human chromosomes have roughly 25,000 genes, how many proteins do they produce?
~100,000 proteins
Where does mitosis occure?
Somatic cells/body cells (everywhere else)
Where does Meiosis occur?
Only in ovaries and testes during the formation of gametes
What is the product of Mitosis?
2 diploid cells
What is the product of Meiosis?
4 haploid cells
What results from Mitosis?
growth and repair
What results from Meiosis?
gamete (egg and sperm) production
Mitosis involves no exchange of what?
genetic material
What is exchanged in Meiosis?
parts of chromosomes are exchanged in crossing over
The daughter cells from Mitosis are _______ _______
genetically identical
Daughter cells in Meiosis are:
not genetically identical
the process of allowing too many or not enough chromosomes
nondisjunction
Example of an allele
Hair color is determined by multiple genes
Why are nucleotides called bases?
they are nitrogen containing bases
What are made out of nucleotides?
DNA and nucleic acids
List the nucleic acids
mRNA, rRNA, and tRNA