Unit 2: Genetics Flashcards by Reyhana Rahimi

DNA stands for:

Deoxyribonucleic acid

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DNA is made up of

carbon, oxygen, hydrogen, nitrogen and phosphorus atoms

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Polymers are

long chains of repeating subunits

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The subunits of DNA are called

nucleotides

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Nucleotide is made up of

ringed structure molecule called deoxyribose
a phosphate group
one of the 4 ringed nitrogen bases (thymine, adenine, cytosine, guanine)

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the chemical bond that links nucleotides together is called

a phosphodiester bond. This forms the sugar-phosphate backbone.

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2 types of nitrogen bases

Purines: double-ringed structure
Pyrimidines: single-ring structure

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A complete DNA molecule is formed when

2 chains linked together by hydrogen bonds formed by complementary nitrogen base pairs in each strand

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hydrogen bonds are NOT

a chemical bond but rather a very strong intermolecular force

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which of the nitrogen bonds is the strongest?

Guanine and Cytosine (triple bond), while Adenine and Thymine have a double bond

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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)

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prokaryotic cells have

one circular chromosome

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eukaryotic cells have

multiple pairs of linear chromosomes contained within the nucleus

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Humans have

23 pairs of chromosomes or 46 linear pieces

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each chromosome is a

specific length, similar partner with the exception of the 23rd pair or sex chromosomes

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Mitosis-

makes identical body cells like skin cells and stomach cells, important for growth or repairing damage or replacing a won out cell

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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)

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PMAT is?

prophase, metaphase, anaphase and telophase

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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

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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)

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the instructions for DNA are:

“spelled out” in a sequence of nitrogen bases and are carried out by proteins

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proteins are:

enzymes that control almost every chemical reaction that occurs in the cell, also are long chains of amino acids

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The chain of amino acids is called

a polypeptide chain

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Hemoglobin is

a protein found in red blood cells

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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

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

Unit 2: Genetics Flashcards

(75 cards)