Unit 2: Genetics Flashcards
DNA stands for:
Deoxyribonucleic acid
DNA is made up of
carbon, oxygen, hydrogen, nitrogen and phosphorus atoms
Polymers are
long chains of repeating subunits
The subunits of DNA are called
nucleotides
Nucleotide is made up of
- ringed structure molecule called deoxyribose
- a phosphate group
- one of the 4 ringed nitrogen bases (thymine, adenine, cytosine, guanine)
the chemical bond that links nucleotides together is called
a phosphodiester bond. This forms the sugar-phosphate backbone.
2 types of nitrogen bases
Purines: double-ringed structure
Pyrimidines: single-ring structure
A complete DNA molecule is formed when
2 chains linked together by hydrogen bonds formed by complementary nitrogen base pairs in each strand
hydrogen bonds are NOT
a chemical bond but rather a very strong intermolecular force
which of the nitrogen bonds is the strongest?
Guanine and Cytosine (triple bond), while Adenine and Thymine have a double bond
The DNA molecule twists in such a way that it forms a
minor and major groove (allows for specific binding on enzymes and proteins such as histones to the DNA)
prokaryotic cells have
one circular chromosome
eukaryotic cells have
multiple pairs of linear chromosomes contained within the nucleus
Humans have
23 pairs of chromosomes or 46 linear pieces
each chromosome is a
specific length, similar partner with the exception of the 23rd pair or sex chromosomes
Mitosis-
makes identical body cells like skin cells and stomach cells, important for growth or repairing damage or replacing a won out cell
Meiosis-
contributes to genetic variety, does not make body cells, instead makes sperm and egg cells (gametes). DNA is replicated before the process even starts but still has 46 chromosomes but 92 chromatids (counted by centromeres)
PMAT is?
prophase, metaphase, anaphase and telophase
Mitosis process:
P1- chromosomes condensing (thickening)
M1- chromosomes line up in the middle (single-file line)
A1- Chromatid pulled away by spindles (moving to opposite sides)
T1- new nuclei forming on each side making 2 new cells
Cytokinesis then occurs (splits), and ends with 2 identical diploid cells
Meiosis process:
P1- matches with homologous pairs (crossing over)
M1- in the middle of the cell but still in pairs (independent/ assortment)
A1- chromosomes being pulled away to opposite sides (homologous pairs apart, sister chromatids together)
T1- chromosomes at the opposite ends and new nuclei forming on each side to make 2 new cells
cytokinesis follows to split cytoplasm to complete dividing
P2- chromosomes condensing in both cells
M2- in the middle but this time in single-file
A2- chromatids getting pulled away
T2- chromosomes at complete opposite ends and new nuclei forming on each side to make new cells
cytokinesis follows to completely split cytoplasms, ends with 4 non-identical cells (gametes)
the instructions for DNA are:
“spelled out” in a sequence of nitrogen bases and are carried out by proteins
proteins are:
enzymes that control almost every chemical reaction that occurs in the cell, also are long chains of amino acids
The chain of amino acids is called
a polypeptide chain
Hemoglobin is
a protein found in red blood cells
What is the difference between RNA and DNA?
they have a sugar ribose, and instead of thymine there is uracil
Transcription is:
DNA is separated into single strands and copied into a temporary strand of messenger RNA (mRNA)
Translation is:
mRNA used to create polypeptide chain
errors in meiosis lead to
errors in chromosome numbers in gametes
embryos that develop from these nondisjunction gametes will
have missing or extra chromosomes
4 types of damage that can occur to chromosomes during meiosis?
duplication, deletion, inversion and translocation
when does non-disjunction happen?
when homologous chromosomes do not separate during anaphase 1 or 2, nondisjunction occurs
what is translocation?
occurs when a fragment of one chromosome attaches to a non-homologous chromosome
what is deletion?
occurs when a fragment of one chromosome is lost
what is duplication?
occurs when part of a chromosome is repeated
what is an inversion?
reverses a fragment of the original chromosome
DNA replication occurs during what phase?
S phase
joining occurs at
centromeres
each time the linear chromosomes of eukaryotic cells divide a small amount of what is lost?
DNA is lost from the tips of the chromosomes
what are the protective caps called?
telomeres, they don’t have protein coding (if the cell is divided enough the telomere could be completely used up)
What is critical in the cell cycle?
timing and regulation, critical for normal growth and development
checkpoints are
set up to help detect mutations or potential problems in the cell during the cycle
Apoptosis is
programmed cell death
what happens if a problem is detected in the cell?
when they are detected at the checkpoints, the cell is destroyed in a controlled way to minimize damage to the surrounding cells and recycle as much material as possible.
what happens if a cell is reproducing in the wrong time or place?
may form a mass of cells called a tumour
Malignant tumours are:
a result of the reproduction of cancer cells
somatic cells of multi-cellular organisms use what to replicate?
mitosis and cell division
what is NOT chemically bound in deoxyribose in DNA?
another deoxyribose
which nitrogen bases are purine?
adenine and guanine
when DNA forms a double-strand
the nitrogen base part of the nucleotide joins with the complementary strand
What are the complementary base pairs?
Adnenine -> thymine
Guanine -> cytosine
chromosomes are:
a way of organizing and compacting DNA
a sugar-phosphate backbone is formed between
deoxyribose and a nitrogen base
chromosomes contain:
nucleosome structures and histone proteins
genetic material of a cell is composed of
deoxyribonucleic acid
bacteria do NOT
have DNA enclosed in its nucleus
chromosome is:
long, condensed DNA molecule in eukaryotic cell
chromatin is:
mass of long fibres consisting of DNA and proteins in the nucleus of eukaryotic cells
Histone is:
protein that DNA wraps itself around to form chromatin
nucleosome is:
bead of DNA and protein that protect the genetic information and prevent tangling
what are the 3 bases of a section called?
a codon
chromsomes presnet in a human somatic cell is
46
what phase of the cell cycle does mitosis occur in?
M phase
Two ways that allow for genetic variation
- independent/ random assortment, which happens in metaphase 1
- crossing over, which happens in prophase 1
fertilization of 2 gamete cells results in
a diploid zygote
karyotypes are
when condensed chromosomes can be stained and photographed
Who made the classification of genetic material?
Austrian monk, Gregor Mendel (1822-1884)
What was Mendel’s hypothesis?
that those plants passed down separate and distinct factors to their offspring and were responsible for hereditary traits
what were his experiments?
with pea plants, and true breeding yellow-green seeds
The law of independent assortment states
genes that segregate independently in meiosis do not influence each other inheritance
The law of segregation states
that the two alleles for a trait or genes segregate (separate) during the phases of meiosis
what is an allele?
different versions of genes, dominant or recessive
what are the different trisomys?
Trisomy 13- patau syndrome
Trisomy 18- Edwards syndrome
Trisomy 21- down syndrome
XXY- Klinefelter syndrome
XXX- triple x
how many alleles are there for human blood types?
3 (I^A, I^B, i)
chromosomes in a karyotype represent…
two chromosomes, one inherited from mother and father, and are similar to one another
in humans, blood type is expressed as
dominant and recessive, and codominant
