The cell, DNA and chromosomes Flashcards
Define biology:
A science that explore sliving things and lifeprocesses
What is the basic unit of all living matter?
Cells
What are the 3 main requirements of the body?
- Provide food as a source of raw material for the release of energy
- Supply oxygen to help break down food
- Have enough water to transport inorganic substances into and out of the cell
What are the four main structures that make up a human cell?
- Cell membrane
- Cytoplasm
- Cytoplasmic organelles
- Nucleus
List the cytoplasmic organelles:
- Edoplasmic reticulum
- Golgi apparatus/complex
- Mitochondria
- Lysosomes
- Ribosomes
- Centrosomes
What is contained within a nucleus?
- DNA
Nucleolus
What is the function of the endoplasmic reticulum?
Enables the cell to communicate with the extracellular enviorment and transfers food from one part of the cell to another
What is the function of the golgi apparatus?
- Unite large carb molecules and combines them with protiens to form glycoprotieins
- Transfers enzymes and hormones through the cell membrane to exit cell, enter the blood and be carried to areas where they are required
What is the function of the ribosomes?
Manufactures the various protiens that cells requrie
What is the function of the centrosomes?
Play some part in the formation of the mitotic spindle during cell division
What do atoms make up?
Molecules
What makes up cells?
Molecules
What is the atomic composition of the body?
- 60% hydrogen
- 25..7% O2
- 10.7 % Carbon
- 2.4% Nitrogen
- 1% Calcium, phosphorus, sulfur
What is the molecular composition of the body?
- 80% water
- 15% proteins
- 2% lipids
- 1% Carbohydrates nucelic acids, other
What is considered to be the most critical and radiosensitive target molecule?
Nucleic acid (DNA)
What percentage of nucleic acids make up in the cell?
Nucleic acids comprise approx 1% of the cell
T/F
Nucleic acids are very large, complex macromolecules
True
What are the 2 types of nucleic acids that cells contain?
- RNA
- DNA
What are the 2 DNA compounds?
- Purines
- Pyrimidines
What are purines?
2 carbon-hydrogen rings
What are pyrimidines?
1 Carbon-hydrogen ring
What are the purines of the DNA?
- Adenine
- Guanine
What are the pyrimidines of the cell?
- Thymine
- Cytosine
What are the pairings of the DNA between pruines and pyrimidines?
A pairs with T
G pairs with C
What type of bonds attach the bases to eachotehr within the DNA?
Hydrogen bonds
What makes up the double helix configuration in DNA?
2 long sugar phosphate chains that twist around eachother
How is the double helix configuration linked?
Linked by pairs of nitrogenous organic bases at the sugar molecule of the chain
How many base pairs are there in the human body?
2.9 billion
How does DNA determine a persons characterisitcs?
By regulating the sequence of amino acids in the persons constituent proteins during synthesis of these proteins
What makes up a genetic code?
The sequence of nitrogenous base pairs in a DNA molecule
(base pairing)
What are chromosomes?
They are tiny rod shaped bodies that under a microscope appear to be long threadlike structures that become visible only in dividing cells
What are chormosomes composed of?
Protein and DNA
How many chromosomes does a normal human have in each somatic (non reproductive) cell?
46 chromosomes (23 pairs)
How many chromosomes do germ cells (reproductive cells) have?
23 chromosomes each
T/F
Approximetely 30000 genes are capable pf producing 90000 different proteins
True
What are genes responsible for?
They contian info responsible for;
1. DIrecting cytoplasmic activity
2. Controlling growth and development of cell
3. Transmitting hereditary information
4. Control the formation of proteins in every cell through genetic coding
What are the 2 effects of radiation exposure on the cell?
- Cells die
- Cells behave abnormally
What are the 2 general types of cells?
- Somatic cells-Body cells
- Genetric or germ cells
What are the 2 types of cell division that occur in the body?
- Mitosis
- Meiosis
What is meiosis?
A process of cell division that reduces the number of chromosomes in a each daughter cell to half the number of chromosomes in the parent cell
What is mitosis?
A process that occurs when all somatic cells divide
T/F
In mitosis, the nucleus divides frist, followed by the division of the cytoplasm.
True
What are the four subphases of mitosis?
- Prophase
- Metaphase
- Anaphase
- Telophase
What are the phases of interphase?
G1, S, G2
What is interphase?
The period of cell growth that occurs before actural mitosis
What is the S phase?
S phase is when each DNA molecule is replicated and then divided into 2 sister chromatids
T/F
Each DNA molecule is replicated into 2 identical daughter chromosomes
True
What is a chromatid
It is one of 2 duplicated protions of DNA in a relicated chromosome that appears during cell division
If radiation exposure reaches the cell during metaphase, what can occur?
- The cell dicision can be stopped
- Chromosome damage (results in an approx equal distribution of all cellular material between the 2 daughter cells)
T/F
We can see damage caused by radiation during metaphase under a microscope.
True
Watch videos on mitosis
Lecture 6
Where is the major difference between meiosis and mitosis?
The major difference begins at the end of telophase
What occurs during crossover in meiosis?
Sister chromatids exchange some chromosomal material (genes)
What does crossover result in?
Changes in genetic compositions and trainst taht can be passed on to future generations
What are homologs?
2 of each gene of a somatic cell located on 2 different chromosomes
How many pairs of homologous chromosomes do humans have?
23 pairs
What is a diploid?
The presence of two complete sets of chromosomes in an organism’s cells
What are the immature germ cells called in males?
Called spermatogonia
What are the immature germ cells called in females?
Oogonia
What are mature germ cells called in females?
Ova or egg
What are mature germ cells called in males?
Sperm or spermatozoa
How many chromosomes do immature germ cells have?
46 chromosomes
How many chromosomes do mature germ cells have?
23 chromsomes
What is ploidy?
The number of sets of chromosomes in a cell
T/F
Ussually a gamete carries a full set of chromosomes that includes a single copy of each chromosome.
True
What is the haploid number?
It is the number of chromosomes in a gamete (n)
What do two gametes form?
A diploid zygote with twice the number of chromosomes
What does a zygote become?
An embryo
Watch videos on meiosis
Lecture 6
Label the phases of meiosis:
- Interphase
- Prophase 1
- Metaphase 1
- Anaphase 1
- Telephase 1 & cytokenesis
- Prophase 2
- Metaphase 2
- Anaphase 2
- Telephase 2 and cytokenesis
Pictures for understanding
Miosis for understanding
What are the 4 classes of Organic Compounds?
- (Proteins, Carbohydrates, Lipids (fat), Nucleic Acids)
