Genetics Unit 1 Flashcards
What is a somatic cell?
A somatic cell is another word for human body cell.
Every human is comprised of approximately how many cells?
60 trillion cells.
How many chromosomes are in a human body cell?
46 chromosomes.
How many pairs of chromosomes?
23 pairs of chromosomes.
What is a Gene?
Section of DNA that codes for a particular protien/trait.
What is a Karyotype?
An illustration or photograph of the chromosomes in the nucleus of a somatic cell in an organism.
How are chromosomes sorted in karyotypes?
Sorted by size, centromere location and banding patterns.
What is the point of karyotypes?
To identify chromosome abnormalities such as looking for missing, extra, or damaged chromosomes.
What is a Homologous pair?
One comes from mom other from dad, visually looks same, codes for the same trait in the same location.
How many pairs of Autosomes (non sex chromosomes) do humans have?
22 pairs of Autosomes (non sex chromosomes).
How many pairs of sex chromosomes do humans have?
1 pair of sex chromosomes.
Female genotype is?
XX
Male genotype is
XY
What does DNA stand for?
Deoxyribonucleic Acid.
What year and who was it who determined that DNA molecuels form a helical shape using x-ray crystallograph?
In 1951, Rosalind Franklin determined that DNA molecuels form a helical shape.
What year and who was it who determined the structure of DNA?
In 1953, James Watson and Francis Crick determined the structure of DNA.
DNA is made up of 3 parts, they are?
1)Phosphate, 2)Deoxyribose sugar, 3)Nitrogen base
There are 4 different Nitrogen bases, what are they?
Adenine, Thymine, Guanine, Cytosine.
What is a Nucleotide?
Building block of DNA consisting of one phosphate, one sugar, and one nitrogen base.
Difference between DNA and RNA
DNA is double stranded, has deoxyribose sugar, and contains adenine, thymine, cytosine, and guanine.
Difference between DNA and RNA (2)
RNA is single stranded, has ribose sugar, and contains adenine, uracil, guanine, and cytosine.
___ Always binds with ___
G (Guanine), C (Cytosine)
___ Always binds with ___
A (Adenine), T (Thymine)
What is Purine bases?
Bases with two nitrogen rings (bigger)
What is Pyrimidine base?
Bases with one nitrogen ring (smaller)
What is a haploid?
A cell containing half the usual complement of chromosomes (n).
What is a diploid?
A cell containing two copies of each chromosome (2n).
What is a gamete?
An egg (ovum) and sperm cells, these are specialized sex cells that unite to form a zygote.
What number (n) of crhomosomes do sex cells contain?
sex cells contain haploid cells (n).
What number (n) of chromosomes do somatic cells contain?
Somatic cells contain diploid cells (2n).
What is the longest cycle in the cell cycle?
Interphase (about 90% of time is spent in interphase)
What is Interphase?
The growth stage
What happens in the G1 phase?
Cell Growth, production of protiens and organelles.
What happens in the S phase?
Synthesis of DNA
What happens in the G2 phase?
Preperation of mitosis.
What is the purpose for cell division?
To replace dead and damaged cells/old cells, growth.
What are the 4 stages of mitosis (PMAT)?
1) Prophase, 2) Metaphase, 3) Anaphase, 4) Telophase
What happens during Prophase?
Chromatin coils up to form chromosomes, Nucleolus and nuclear membrane disappear,Centrioles separate and move to opposite ends, Spindle fibres begin to form at the centrioles and stretch across the cell, Spindle fibres attach to one side of each centromere
What happens during Metaphase?
Double stranded chromosomes line up along the middle of the cell (the metaphase plate or equator)
What happend during Anaphase?
Spindle fibres begin to shorten and contract, Centromeres are separated, Each chromosome splits into TWO sister chromatids, The two sister chromatids move to opposite ends of the cell
What happens during Telophase?
Spindle fibres disapear, Nuclear membrane forms around each set of chromosomes, Nucleolus appears within each nucleus, Single-stranded chromosomes start to uncoil into thin strands of chromatin
When does Cytokinesis occur?
After telophase.