Unit C2: Cell division, genetics, and molecular biology Flashcards
Crossing-over
- Occurs between non-sister chromatids during meiosis.
- Creates four types of gametes in a dihybrid instead of two.
- Produces recombinant gametes with new gene combinations.
- Helps determine gene order on a chromosome.
Happens more often between distant genes than closer ones.
Dihybrid
An organism heterozygous for two genes, producing four types of gametes.
independent assortment
Genes on different chromosomes separate randomly during gamete formation.
locus linkage group
Locus: The specific location of a gene on a chromosome.
Linkage Group: Genes located on the same chromosome that tend to be inherited together.
autosomes
Non-sex chromosomes that are the same in both males and females.
carrier
An individual who has one recessive allele for a trait but does not express it.
colour blindness
A genetic condition where an individual has difficulty distinguishing certain colors, usually red and green.
Duchenne muscular dystrophy
A genetic disorder causing progressive muscle weakness, primarily affecting boys, due to a mutation in the dystrophin gene.
hemophilia
A genetic disorder where blood doesn’t clot properly, leading to excessive bleeding from injuries, caused by a deficiency in clotting factors.
sex chromosomes
Chromosomes that determine an individual’s biological sex; XX for females and XY for males.
X-linked genes
Genes located on the X chromosome, often affecting males more since they have only one X chromosome.
Y-linked genes
Genes located on the Y chromosome, typically determining male traits and passed from father to son.
Down syndrome
A genetic disorder caused by trisomy 21 (an extra copy of chromosome 21), leading to developmental delays and characteristic physical features.
karyotype
A visual representation of an individual’s chromosomes, arranged by size and shape, used to detect genetic abnormalities.
Klinefelter syndrome
A genetic condition in males caused by an extra X chromosome (XXY), leading to symptoms like reduced fertility, less muscle mass, and learning difficulties.
monosomy
genetic condition where an individual is missing one chromosome (2n - 1), often leading to developmental disorders.
nondisjunction
The failure of chromosomes to separate properly during meiosis, leading to gametes with extra or missing chromosomes.
polyploidy
A genetic condition where an organism has extra sets of chromosomes (e.g., 3n or 4n), common in plants but rare in animals.
trisomy
A genetic condition where an individual has an extra chromosome (2n + 1), leading to disorders like Down syndrome (trisomy 21).
turner syndrome
A genetic disorder in females caused by a missing or incomplete X chromosome (XO), leading to short stature, infertility, and developmental differences.
adenine
Adenine (A): A purine nitrogenous base in DNA and RNA that pairs with thymine (T) in DNA and uracil (U) in RNA through two hydrogen bonds.
antiparallel
The two strands of the DNA double helix run in opposite directions—one 5’ → 3’, the other 3’ → 5’—allowing for proper base pairing and replication.
complementary bases
Nitrogenous bases in DNA that pair specifically through hydrogen bonds—Adenine (A) pairs with Thymine (T) (2 bonds), and Guanine (G) pairs with Cytosine (C) (3 bonds).
cytosine
A pyrimidine nitrogenous base in DNA and RNA that pairs with guanine (G) through three hydrogen bonds.
deoxyribose
A five-carbon sugar in DNA that forms part of the nucleotide backbone, lacking one oxygen atom compared to ribose in RNA.
DNA
A double-stranded molecule that stores genetic information, made of nucleotides with a deoxyribose sugar, phosphate group, and nitrogenous bases (A, T, G, C).
double helix
The twisted ladder shape of DNA, with two antiparallel strands held together by complementary base pairing (A-T, G-C).
guanine
A purine nitrogenous base in DNA and RNA that pairs with cytosine (C) through three hydrogen bonds.
nitrogenous base
A molecule that contains nitrogen and forms the building blocks of DNA and RNA. In DNA, the bases are adenine (A), thymine (T), guanine (G), and cytosine (C), and in RNA, thymine is replaced by uracil (U). These bases pair to form the structure of the genetic code.
nucleotide
The basic building block of DNA and RNA, consisting of a phosphate group, a deoxyribose (in DNA) or ribose (in RNA) sugar, and a nitrogenous base (A, T, G, C in DNA; A, U, G, C in RNA).
phosphate
A chemical group consisting of a phosphorus atom bonded to four oxygen atoms. It is a key component of the backbone of DNA and RNA, linking the sugar molecules of adjacent nucleotides.
purine
A type of nitrogenous base with a two-ring structure. In DNA and RNA, the purines are adenine (A) and guanine (G). They pair with pyrimidines in the DNA structure (A with T, G with C).
pyrimidine
A type of nitrogenous base with a single-ring structure. In DNA and RNA, the pyrimidines are cytosine (C), thymine (T) (in DNA), and uracil (U) (in RNA). They pair with purines in DNA (C with G, T with A).
thymine
A pyrimidine nitrogenous base in DNA that pairs with adenine (A) through two hydrogen bonds. Thymine is not found in RNA, where it is replaced by uracil (U).
complementary strand
The strand of DNA that is formed based on the base-pairing rules, where adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C). It is complementary to the original (template) DNA strand and is synthesized during DNA replication.
DNA helicase
An enzyme that unwinds and separates the double-stranded DNA by breaking the hydrogen bonds between complementary base pairs, creating the replication fork during DNA replication.
DNA ligase
An enzyme that joins the Okazaki fragments on the lagging strand by forming phosphodiester bonds between them during DNA replication.
DNA polymerase
An enzyme that adds nucleotides to the growing DNA strand during replication, synthesizing DNA in the 5’ to 3’ direction.
DNA replication
The process of copying a DNA molecule to produce two identical DNA molecules, ensuring genetic information is passed on to daughter cells.
lagging strand
The DNA strand that is synthesized discontinuously in small segments called Okazaki fragments during DNA replication.
leading strand
The DNA strand that is synthesized continuously in the same direction as the replication fork during DNA replication.
Okazaki fragments
Short segments of DNA synthesized on the lagging strand during DNA replication, which are later joined together by DNA ligase.
semiconservative
The model of DNA replication where each new DNA molecule consists of one original strand and one newly synthesized strand.
template
The original strand of DNA that serves as a guide for the synthesis of a complementary strand during DNA replication. The template strand determines the sequence of nucleotides in the newly synthesized strand.
anticodon
A three-nucleotide sequence on tRNA that is complementary to the mRNA codon and ensures the correct amino acid is added during protein synthesis.
codon
A three-nucleotide sequence on mRNA that codes for a specific amino acid or signals the start or stop of protein synthesis.
gene
A segment of DNA that contains the instructions for making a specific protein or RNA molecule.
gene expression
The process through which information from a gene is used to synthesize a functional protein or RNA, involving transcription and translation.
mRNA
A type of RNA that carries the genetic code from DNA in the nucleus to the ribosome, where it is translated into a protein.
rRNA
A type of RNA that makes up part of the ribosome and helps catalyze the formation of peptide bonds between amino acids during protein synthesis.
start codon
The AUG codon on mRNA that signals the beginning of protein synthesis and codes for the amino acid methionine.
stop codon
A codon (such as UAA, UAG, or UGA) that signals the end of protein synthesis and does not code for any amino acid.
transcription
The process where a DNA sequence is copied into mRNA, allowing the genetic information to be transferred from the DNA to the cytoplasm for protein synthesis.
translation
The process by which mRNA is decoded by the ribosome, and tRNA molecules bring the correct amino acids to build a polypeptide chain (protein) based on the mRNA sequence.
triplet code
The three-nucleotide sequence in DNA or mRNA that codes for a specific amino acid. Each triplet is called a codon.
tRNA
A type of RNA that carries specific amino acids to the ribosome during translation and has an anticodon that pairs with the corresponding mRNA codon.
uracil
A pyrimidine base in RNA that pairs with adenine (A) during transcription. It replaces thymine (T) found in DNA.
frameshift mutation
A mutation caused by the insertion or deletion of nucleotides, altering the reading frame of the genetic code and often resulting in a nonfunctional protein.
gene mutation
A change in the DNA sequence of a gene that may affect the structure or function of the protein encoded by the gene.
mutagen
Any agent, such as chemicals, radiation, or viruses, that can cause a change (mutation) in the DNA sequence of an organism.
nonfunctional protein
A protein that has an altered structure or loss of function due to a mutation, preventing it from performing its biological role.
point mutation
A mutation that involves the substitution of a single nucleotide in the DNA sequence, potentially affecting a single amino acid in the protein.
silent mutation
A mutation that changes a nucleotide in the DNA sequence but does not affect the amino acid sequence or the function of the protein.
transposon
A DNA sequence that can move or transpose to different locations within the genome, often causing mutations or changes in gene expression.
cloning
The process of creating an identical copy of an organism, cell, or DNA fragment. It involves duplicating the genetic material to produce genetically identical organisms or cells.
DNA sequencing
A laboratory method used to determine the exact order of nucleotides (A, T, C, G) in a DNA molecule, helping to map genes and genetic information.
gene cloning
The process of making copies of a specific gene by inserting it into a vector (e.g., plasmid) and allowing it to replicate within a host organism, such as bacteria.
genetic engineering
The manipulation of an organism’s DNA to alter its genetic makeup, often to introduce new traits or improve existing ones. This includes the use of technologies like gene cloning and CRISPR.
genetic transformation
The process of introducing new genetic material (e.g., a gene or DNA) into an organism’s cells, resulting in a genetically modified organism (GMO).
genome
The complete set of genetic material (DNA) present in an organism, including all of its genes and non-coding sequences.
PCR
A laboratory technique used to amplify a specific segment of DNA, making millions of copies of a targeted region to study or manipulate it.
restriction enzymes
Proteins that act as molecular scissors, cutting DNA at specific sequences. They are used in cloning and DNA analysis.
STR
Repeating DNA sequences of 2-6 base pairs in length that are highly variable between individuals and are used in DNA profiling and forensic identification.
transgenic organisms
are organisms that have been genetically modified by introducing a gene from another species into their genome. This foreign gene, often called a transgene, confers new traits or abilities to the organism. Transgenic organisms are commonly used in agriculture (e.g., genetically modified crops like Bt corn), medicine (e.g., animals producing therapeutic proteins), and research, allowing for the production of new substances or improved characteristics.
biotechnology products
Products created using biotechnological techniques, such as genetically modified organisms (GMOs), therapeutic proteins, vaccines, and biofuels, to benefit industries like medicine, agriculture, and energy.
gene pharming
The use of genetically modified animals or plants to produce pharmaceutical products (e.g., proteins, hormones) in their milk, eggs, or tissues. This process is used for drug production.
GMO
An organism whose genetic material has been altered in a way that does not occur naturally through mating or natural recombination. GMOs are often engineered to possess specific traits like pest resistance or enhanced nutrition.
transgenic
Referring to an organism that has been genetically modified by introducing a gene from another species, making it transgenic due to the presence of foreign genetic material.
