DNA - Overall Study Flashcards
What is the name of the molecule of genetic code that leaves the nucleus of the cell during translation?
mRNA
Who made the Watson-Crick model?
James Watson and Francis Crick
Define genetics
The study of inherited traits
What three parts make up nucleotides?
Phosphate group, deoxyribose sugar (pentose sugar)`, nitrogen-rich bases
What was the first successful DNA model?
The Watson-Crick model?
TRUE or FALSE
The genes that code for a particular characteristic are located on different parts of the paired autosomes.
False - They are located at the same parts of paired autosomes.
What are the three characteristics of homologous chromosomes?
- Same length
- Have a structure called the centromere
- Have genes for particular characteristics at the same location along their length.
What does asexual reproduction rely on?
Mitosis
What are the three steps of DNA replication?
- The strands of DNA separate from each other (unzip)
- Nucleotides that are not yet part of a DNA chain pair up with the exposed nucleotides.
- Zips back up
Define meiosis
The process of cell division that produces gametes - sperm and egg cells
What is a chromosome?
A long, thin, thread-like structure found in the nuclei of all cells that contain a nucleus.
What causes mutations?
Either spontaneously (due to a fail in replication) or damage to a strand of DNA.
What are the smaller molecules that make up the structure of DNA called?
Nucleotides
Give an example of a mutagen caused by radiation
X-rays, radioisotopes, UV light
Give an example of a mutagen caused by something biological
Hepatitis B, cervical cancer
Give an example of a mutagen caused by something chemical
Cigarette smoke, asbestos, mustard gas
What are the different types of mutations?
Silence mutation. Missense. Nonsense. Frameshift
What does a silence mutation do?
Nothing, it does not affect the individual
What does a missense mutation do?
Causes the wrong protein to be produced
What does a nonsense mutation do?
The code abruptly ends, stopping the production of proteins
What does a frameshift mutation do?
Insertion or deletion of bases. The information becomes jumbled and impossible to read.
What are the groups of proteins?
Structural. Enzymes. Regulatory
Define genes
Genes are sections of DNA arranged along the chromosomes
Define ribosomes
A molecular machine that builds proteins from amino acids
What forms the backbone of the DNA molecule?
Phosphate group and the deoxyribose sugar.
What does a gene code for?
A specific protein
What are homologous chromosomes?
A pair of autosomes
How many chromosomes are in the human body?
46 (23 pairs)
What are gametes?
Sperm and egg cells
What are the stages of meiosis
Prophase, crossover, metaphase1, anaphase1, telophase1, metaphase2, anaphase2, telophase2
What case-letter is the dominant trait represented with?
uppercase
What case-letter is the recessive trait represented with?
lowercase
Define codon
Bases arranged in triplets; a series of bases
Define translation
When RNA is read by the ribosomes
Give an example of an organism that reproduces asexually.
Hydra, yeasts, grasses
What happens within metaphase?
Chromosomes meet in the middle and become attached by spindle fibers.
Define replication
The process of copying DNA
What happens within interphase?
The genetic material doubles and prepares to divide
Define phenotype
The observable characteristic of the individual
What are the complementary base pairings?
Adenine thymine
Guanine cytosine
What is cytokinesis?
The final stage of mitosis; when the cell divides
What sex chromosome pair determines the female sex?
XX
What sex chromosome pair determines the male sex?
XY
What does DNA stand for?
Deoxyribonucleic acid
What are the non-sex chromosomes called?
autosomes
What are the stages of mitosis?
Interphase, prophase, metaphase, anaphase, telophase, cytokinesis
What is the advantage of sexual reproduction in comparison to asexual reproduction?
There is greater variation within offspring
Define mutagen
Agents that cause mutations
What is a sex-linked gene?
A gene found on one of the chromosomes that determine the sex of offspring
Which backbone of the DNA molecule do the nitrogen-rich bases join to?
Phosphate group
What reads codons?
Ribosomes
Define transcription
The process of DNA being copied to RNA
What are the four nitrogen-rich bases?
Adenine (A), thymine (T), guanine (G), cytosine (C)
What happens within anaphase?
Chromosomes get pulled apart by the spindle fibers. There is now one chromatin on each side
What is a centromere?
The point on a chromosomes where the two chromatids are joined together.
TRUE or FALSE
Daughter cells are not genetically identical to the parent cell.
FALSE
Where are chromosomes located?
In the nucleus of a cell. DNA can be found in the mitochondria or chloroplasts
What happens within telophase?
Chromosomes uncoil in chromatids. Spindle fibers disintegrate. Centrioles replicate. Membrane is formed.
What is asexual reproduction?
Offspring that isn’t produced by the union of gametes and is instead produced through mitosis.
What is Chargaff’s rule?
There is a similar amount of adenine and thymine as there is to guanine and cytosine.
Define DNA
The molecule that determines the specific characteristics of an individual
Explain why gametes have to have half the diploid number of chromosomes (2n).
If each parent passed on a complete set of genetic information, the offspring would 4n chromosomes. Then their offspring would have 8n and so on.
What is a mutation?
A mutation is when a mistake occurs in the copying of DNA
Are mutations always dangerous? Why?
No. They can create different or even beneficial versions of a protein. Mutations can add to the diversity of organisms
Define carcinogen
A mutation that causes cancer
TRUE or FALSE
Any pair of alleles that has a dominant trait present will produce that dominant trait.
True
Explain Punnett squares
Punnett squares are a visual way of showing all the possible types of offspring that results from a cross.
Define genotypes
The actual genetic information carried by an individual
What happens within prophase?
Chromatids join by the centromere. Centrioles move to opposite sides of the nucleus. Nucleolus disappears. Nuclear membrane disintegrates.
