Genetics Lecture Notes

Flashcards based on genetics lecture notes for exam preparation.

What are the three parts of a nucleotide?

Nitrogenous base, sugar, and phosphate.

Describe the nitrogenous base pairing rules in DNA.

Adenine (A) pairs with Thymine (T) – 2 hydrogen bonds; Cytosine (C) pairs with Guanine (G) – 3 hydrogen bonds.

What is the structural organization of DNA, from chromatin to DNA?

Chromatin → Chromosome → DNA.

What forms the sides of the DNA ladder?

Sugars and phosphates.

What forms the steps of the DNA ladder?

Nitrogen bases.

How many rings do purines and pyrimidines have?

Purines have 2 rings; pyrimidines have 1 ring.

What type of bonds connect sugars and phosphates, and nitrogen bases in DNA?

Covalent bonds connect sugars and phosphates; hydrogen bonds connect nitrogen bases.

What are chromosomes made of?

DNA and proteins (histones).

Describe the nature of DNA replication (conservative, semi-conservative, or dispersive).

Semi-conservative: one strand is the original, and the other is new.

What is a gene?

A section of DNA that codes for a trait.

What is an allele?

A variation of a gene (dominant or recessive).

Which chromosome is the sex chromosome?

Chromosome 23.

What chromosomes do males have?

XY chromosomes (not homologous).

What are autosomes?

Chromosomes 1-22 (body chromosomes).

What are somatic cells?

Regular body cells.

Which parent determines the sex of their offspring?

Males (XY).

What does a karyotype show?

Shows homologous pairs of chromosomes.

What are oogenesis and spermatogenesis?

Oogenesis occurs in females to produce eggs (ova); spermatogenesis occurs in males to produce sperm.

What are the three tenets of the Cell Theory?

All living organisms are made of cells; the cell is the basic structural and functional unit of all living organisms; all cells come from preexisting cells.

What role does water play at a cellular level?

Maintain cell temperatures, act as a lubricant between organs, tissues, and cells, and act as a carrier for dissolved molecules.

What is genetics?

The study of heredity and variation of living organisms and how genetic info is passed through generations.

Why do cells divide?

Growth, repair, and maintenance.

What is mitosis?

The separation of the cell’s replicated genetic material.

What is a chromosome?

A structure made of condensed chromatin fibres in the nucleus that contains DNA.

What are sister chromatids?

Copies of the chromosomes that were replicated in the S phase.

What two processes make up the mitotic phase?

Mitosis and cytokinesis.

What happens during mitosis?

The duplicated genetic material is distributed equally between two daughter cells.

What happens during cytokinesis?

The cell’s cytoplasm is divided into two.

What happens during prophase?

Chromosomes thicken and shorten, and the nuclear envelope breaks down.

What happens during metaphase?

Chromosomes are aligned at the center of the cell.

What happens during anaphase?

Spindle fibres pull the chromosomes to opposite ends.

What happens during telophase?

Spindle fibres dissolve, and the nuclear membrane begins to form around the chromosome, resulting in two daughter nuclei.

What occurs during cytokinesis?

Cell membrane indentation deepens until the cell is pinched in two.

What monitors growth to ensure the cell cycle continues when it should and stops when it should?

Specific checkpoints in the cell cycle.

What shape does DNA form?

A DOUBLE HELIX or twisted ladder.

What are the three parts of a nucleotide?

A phosphate, a sugar, and a base.

What are the four nitrogenous bases in DNA?

Adenine (A), thymine (T), cytosine (C), and guanine (G).

Which bases are complementary to each other?

A can only bond to T and C to G: these are called complementary base pairs.

What is the genome?

The complete sequence of nucleotides in every cell.

What makes up the sides of the DNA ladder?

Sugars and phosphates.

What makes up the steps of the ladder?

Nitrogen bases.

How are the bases connected?

Hydrogen Bonds: Cytosine triple bonds to Guanine and Adenine double bonds to Thymine.

What are the structures of purines and pyrimidines in DNA?

Purines have a double-ring structure and consist of adenine and guanine, while pyrimidines have a single-ring structure and consist of cytosine, thymine, and uracil.

What are chromosomes made of?

Condensed DNA and proteins called histones.

What happens to DNA in the S phase of Interphase?

The double helix unwinds and splits.

What is the result of DNA replication?

Half of the strand will be an original, and one will be a newer copy- semi-conservative replication.

What are the types of chromosomes?

Autosomes and sex chromosomes.

What are genes?

The segments of a chromosome that control the expression of a trait.

What are homologous chromosomes?

Appear same length, centromere location, and banding pattern when stained with certain dyes.

What are alleles?

Different forms of a gene.

What are autosomes and sex chromosomes in a karyotype?

Autosomes are chromosomes 1-22, sex chromosomes are XY or XX

Describe sexual reproduction.

Sexual reproduction requires two partners to contribute their sex cells, also known as gametes.

What are gametes?

Sperm cells from males and egg cells from females.

What is a zygote?

A new individual cell.

What is produced by way of meiosis?

Gametes.

What does "n" stand for?

The number of chromosomes in a cell (haploid number).

What is it called when only one set of chromosomes are in a cell?

Haploid (n).

What is is called when two sets of chromosomes are in a cell?

Diploid (2n).

What the goals of meiosis?

Genetic Reduction and Genetic Recombination.

What reduction occurs during genetic reduction stage of meiosis?

From (2n to n).

What happens during genetic recombination?

Chromosome can recombine to produce different combinations of alleles.

What is the goal for reproduction, regarding genetics?

Offspring receive genetic material from both parents.

What is a homologous chromosome?

Two chromosomes of a matching pair, each carries the same series of genes.

How does interphase contribute to meiosis?

The phases of interphase and steps of meiosis are similar to those of mitosis.

What happens to Chromosomes during prophase I of meiosis?

Shorten and Thicken.

What happens to non-sister chromatids during synapsis?

The break apart and re-attach themselves to form new combinations of genetic information.

What process creates an increase of genetic variations during meiosis?

Crossing over.

What occurs during metaphase I?

The tetrads migrate toward the centre of the cell and align their centromeres across the middle of the cell.

What occurs during anaphase I?

Homologous chromosomes move to opposite poles of the cell.

What is produced during telophase I and cytokinesis?

These are now two haploid cells ready to undergo meiosis II.

What happens as a result of crossing over?

The sister chromatids are no longer identical.

How does meiosis II compare to mitosis?

This process is identical to mitosis!.

What occurs during prophase II?

The nuclear membrane dissolves, and spindle fibres begin to form.

What happens during metaphase II?

The chromosomes arrange themselves at the center of the cell with the spindle fibres attached to the centromere.

What happens during anaphase II?

Sister chromatids separate and move to opposite poles of the cell.

What occurs in meiosis II during telophase II?

Separate nuclei begin to form around each group of chromosomes and cytokinesis splits the daughter cells one more time.

What is the net result of meiosis?

Second nuclear division is completed, and the division into the four new haploid cells is official.

What is gametogenesis?

The formation of the haploid sex cells.

What is spermatogenesis?

The production of sperm cells with equal division.

What is oogenesis?

The production of egg cells where the cell does not divide equally through meiosis.

Why do male sperm cells have to swim a long way to fertilize the female egg must be quick?

They cannot be large and slow.

How can female egg cells supply more nutrients?

By being larger, they can supply the egg with more nutrients.

During metaphase I, how are homologous pairs alligned?

Homologous pairs line up IN PAIRS at the equator of the cell.

What is the importance of independent assortment during metaphase I?

As homologous chromosomes randomly sort themselves into gametes the combinations of maternal and paternal chromosomes mixes to create a potentially more diverse population.

What can the majority of DNA errors cause?

DNA errors lead to cell death.

Describe changes in DNA sequence that trigger genetic disorders?

Often, these changes can cause genetic disorders, and since the changes are PART of the organism's DNA, they are replicated in every cell through mitosis.

What is deletion?

A piece of chromosome lost.

What is Duplication?

Identical piece of chromosome occurs twice (or more) in a row on the same chromosome.

What is inversion?

A segment of the chromosome is flipped.

What is translocation?

A portion of one chromosome inappropriately attaches to another chromosome (non-homologous).

What is non-disjunction?

the failure of homologous chromosomes or sister chromatids to separate during meiosis

What is monosomy?

Loss of a chromosome due to nondisjunction.

What is trisomy?

the Gain of a chromosome due to nondisjunction

List symptoms of trisomy 21 (Down Syndrome).

Cognitive disabilities, abnormal hand creases, almond-shaped eyes, flattened face, short

List symptoms of XXY: Klinefelter syndrome (males)

Sexual immaturity (inability to produce gametes), breast swelling

List symptoms of Edward Syndrome (Trisomy 18)

Cognitive and physical disabilities, facial abnormalities, early death

List symptoms of Patau Syndrome (Trisomy 13)

Cognitive and physical disabilities, organ defects, large triangular nose, early death

What are some techniques used with selective breeding?

Artificial Insemination and Embryo Transfer

What is Aritificial insemination?

A process by which collected and concentrated sperm are artificially introduced into the female reproductive system.

What is Embryo transfer?

An artificially fertilized egg is implanted into the uterus of a recipient female.