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.
What is Cytokinesis?
The division of the cytoplasm.
What does cytokinesis do?
The cytoplasm splits into two identical new cells, one around each new daughter cell.
How do animal cells split?
The cleavage furrow forms.
How do plant cells split?
A cell plate forms.
What does checkpoint mean?
stop and go-ahead signals that regulate the cell cycle.
How are cancer cells characterized?
Cancer cells are characterized by abnormal cell division.
What are 2 fundamental ways cancer cells are different than normal cells?
1) Cancer cells divide out of control, 2) Cancer cells can pile up on one another
what does tumor mean?
Abnormal lump of cells.
What does benign tumor mean?
Tumor that remains in one place in the body (non-cancerous).
What does malignant tumor mean?
Tumor that is capable of spreading throughout the body (Cancerous).
What does metastasis mean?
Spread of cancer cells from the initial site to other parts of the body.
Where is radiation therapy (use of radiation) used on?
The site of cancer.
Where is chemotherapy (use of drugs) used on?
The whole body.
What is the purpose of Meiosis?
To produce gametes, egg or sperm cells.
Where does Meiosis occur?
The gonads (ovaries or testes)
Where are egss produced?
In specialized cells called oogonia - diploid cell
Where are sperm produced?
In specialized cells called spermatogonia - diploid cell
How many viable eggs will there be?
1 viable egg and 3 non functional eggs
How many viable sperm cells will there be?
4 viable sperm cells
What is the result of Meiosis?
4 haploid daughter cells
What happens during synapsis?
Homologous chromosomes pair to form a tetrad (tetrad=4 chromatids)
What happens during crossing over?
Homologous chromosomes in tetrad cross over each other, Pieces of chromosomes or genes are exchanged, Produces genitic variation in offspring.
What happens during metaphase I?
Homologous chromosomes align along the equator of the cell (horizontally)
What is Independent Assortment?
Random alignment of maternal/paternal chromosomes at the metaphase plate.
What happens in Anaphase I ?
Homologous chromosomes separate and move to opposite poles.
What happens in cytokinesis I ?
Division of cytoplasm and the cell will now have 2 haploid (n) cells (23 double stranded chromosomes).
What happens in Meiosis I ?
Seperation of Homologous chromosomes.
What happens in Meiosis II ?
Separation of sister chromatids.
What happens during Metaphase II ?
Double stranded chromosomes align along the equator of the cell (vertically).
What happens during Anaphase II ?
Sister chromatids separate and move to opposite poles.
What happens during cytokinesis II ?
Division of cytoplasm and the cell will now form to 4 haploid (n) cells (23 single stranded chromosomes).
What is and what are mistakes in Prophase I ?
Mistakes in Prophase I are incorrect exchange of genetic information during crossing over, some of these mistakes are duplications, deletions, inversions or translocation of genetic materials.
What is duplication?
Attachment of a chromosme fragment to a homolog that is already complete during crossing over.
What is deletion?
Chromosome that lacks genetic information due to failure of chromosome fragment to attach during crossing over.
What is inversion?
Reversed (upside down) order of attachment of a chromosome.
What is translocation?
Attachment of a chromosome fragment to a non-homologous chromosome.
What does non-disjunction mean?
Errors in the separation of chromosomes.
What is the result of a mistake occuring in Anaphase I or II ?
Abnormal number of chromosomes in an egg or sperm cell (extra or missing chromosomes).
What does aneuploidy mean?
Abnormal number of chromosomes.
What does monosomy mean?
Possession of only one of the homologous pair of chromosomes in an other wise diploid cell.
What does polysomy mean?
possession of an extra copy of a particular chromosome (Eg. down syndrome)
What does polyploidy mean?
Possession of more than 2 sets of chromosomes.
What is the abnormality for Supermale syndrome? and what gender does it affect?
Extra Y chromosome (XYY) and it affects males only.
What is the abnormality for Klinefelter syndrome? and what gender does it affect?
Extra X chromosome (XXY) and it affects males only.
What is the abnormality for Triple X syndrome? and what gender does it affect?
Extra X chromosome (XXX) and it affects females only.
What is the abnormality for Turner syndrome? and what gender does it affect?
Only one X chromosome (X) and it affects females only.
What is the abnormality for Fragile X syndrome? and what gender does it affect?
Repetition of CGG on the X chromosome and it affects both males and females.
What is the abnormality for Patau’s syndrome? and what gender does it affect?
Extra chromosome 13 and it affects both males and females.
What is the abnormality for Edwards syndrome? and what gender does it affect?
Extra chromosome 18 and it affects both males and females.
What is the abnormality for Down syndrome? and what gender does it affect?
Extra chromosome 21 and it affects both males and females.
What is the abnormality for Cri-du-chat syndrome? and what gender does it affect?
Partial deletion of chromosome 5 and it affects both males and females.
What are the 2 most popular type of paternal diagnostic testing?
1) Amniocentesis, 2) Chronic villus sampling
What does trait mean?
Any characteristic of living things.
What does heredity mean?
The passing of traits from parents to offspring.
What does genetics mean?
The science that studies the passing of traits
There are 2 types of traits, what are they?
1) Non-inherited traits, 2) Inherited traits
What does non- inherited traits mean?
Trait not passed on from generation to generation.
What does inherited trait mean?
Passed on from generation to generation.
What does allele mean? and how are they represented?
Different form of a gene that codes for a specific trait, they are represented by letters.
What does homozygous mean?
Term decribing an individual with two like alleles for a trait, also called “pure”.
What does heterozygous mean?
Term describing an individual with two unlike alleles for a trait, also called “hybrid’.
What does genotype mean?
Two allele combination which is the genetic makeup of an organism (Eg. TT).
What does phenotype mean?
Physical appearance of an organism (Eg. tall).
