Bio (genetics)

What is a test cross?

rossing a homozygous recessive individual with one expressing the dominant trait to determine whether or not the dominant trait is heterozygous or homozygous.

What are alleles?

Characteristics or features of an organism

What is a genome?

The complete complement of an organisms or viruses genetic material

What is a gene?

A segment of DNA molecule codes a specific trait

What is a locus?

The location of a gene in a chromosome

What is chromatin?

A mass of thread like strands of DNA

What are chromosomes?

Cellular structures of very long DNA, sister chromatids are joined copies of a chromosomes

What are the 3 steps of the cell cycle?

Interphase, Mitosis, cytokinisis

What happens in interphase?

DNA makes a copy, G1 and G2, the in between stages of dviding

Gnot phase?

Resting phase, nothing happens

What is necrosis?

Cells die due to external factors

What is apoptosis?

Programmed and targeted cells

What is a diploid?

Contains 2 complete sets of chromosomes (somatic cells)

What is a haploid?

Contains a single set of unpaired chromosomes (sex cells)

What happens in prophase?

Chromatin condense into chromosomes, nuclear membrane dissolves, spindle fibres form, nucleolus dispersal

What happens in metaphase?

Chromosomes line up in the middle of the cell, with the help of spindle fibers

What happens in anaphase?

Chromosomes separate into 2 identical sets as sister chromatin are pulled to opposite poles of the cell

What is telophase?

Chromosomes reach the poles and unwind, and nuclear membrane forms

What happens in meiosis?

Hereditary material is exchanged

what happens in prophase 1?

Chromatin condenses into chromosomes, homologous chromosomes pair up to make tetrods, crossing over happens in late prophase 1

What is crossing over?

Homologous chromosomes exchange portions of DNA resulting in offspring that are genetically diffrent

What happens in metaphase 1?

Chromosomes line u p across middle, the random assortment of chromosomes happen here

What happens in anaphase 1?

the chromosomes separate independently

What happens in meosis telophase and interphase?

cell begins to divide and can get any combination of chromosomes

How many daughter cells does meosis make?

4

what is aneuploidy?

Having an abnormal amount of chromosomes

What is nondisjunction?

failure of homologous chromosomes to separate in anaphase

What is monosomy?

karyotype missing one chromosome

what is trisomy?

Condition where there are more chromosomes than required

What is a kayrotype?

organised picture of a persons chromosomes

What is klinefelter syndrome?

Male with an extra copy of the x chromosome

What is turner syndrome?

Missing or damaged x chromosome

What does DNA stand for?

Deoxyribonucleic Acid

What did Friendrich miescher do?

Started investigating a compound found in the nucleus of the cell (1869)

What did rosaland frankllin do?

Took an x-ray photo of DNA (1952)

What did watson and crick do?

discribed the features of DNA in franklins picture (1953)

What does DNA consist of?

a dexoyribose sugar, a phosphate and a nitrogen containing a base

What are the purines?

Adenine and Guanine

What are the pyrimidines?

Thymine and cytosine

What are the 3 types of DNA mutation?

Subsatution, Insertion, Deletion

What is dominant inheritance?

Only one copy of the gene needs to have the mutation for it to be expressed

What is recessive inheritance?

2 copies of the mutation in the gene must be present to be expressed

What are sister chromatids?

Joined copies of the orgnial chromosome

What is G1 for?

Growth and preperation

What is the S phase for?

DNA replecation

What is the G2 phase for?

Preparation for mitosis

what happens in cytokinisis?

Cells seperate fully

What is interkenisis?

It is a period of rest between meiosis 1 and meiosis 2

What is Polyploidy?

Nondisjusction of all the the chromosomes

What is DNA wrapped around?

Hitones (protiens)

What kind of backbone does DNA have?

Phosphate sugar

What is the key to diveristy in DNA?

Different arrangements of nuclitoids

What happens when DNA mutates?

It might have no effect, the amino acid may be similar to the one it replaces or it can be deadly

What happens in substitution?

A new base completely replaces the old base

What happens in insertion?

A whole new compound is added, pushing all the bases forward

What happens during deletion?

A base pair is completely taken out, moving the other bases backward

What is genetic screening?

any procedure used to identify individuals with an **increased** risk of passing on an **inherited** disorder.

What is genetic counselling?

The giving of advice to prospective parents concerning the chances of genetic disorders in a future child.

What is a pedigree?

the recorded ancestry, especially upper-class ancestry, of a person or family.

What is prenatal diagnosis?

The purpose of prenatal diagnosis is to test the **fetus** for a genetic problem for which the family is at risk.

What is Amniocentesis?

* __**14-16**__ weeks into pregnancy.
* a needle is pushed through the __**abdominal**__ wall.
* __**amniotic**__ fluid is withdrawn and centrifuged. 

**fetal** cells in the fluid are isolated and a **karyotype** is made.

What is chorionic villus?

* __**9 – 12**__ weeks into pregnancy
* tube inserted __**intravaginally**__
* cells from __**chorionic**__ membrane are suctioned out

**fetal** cells are isolated and a **karyotype** is made

What is   Recombinant DNA?

The purpose is to produce missing **proteins** to allow us to treat people with **defective** genes.

What is gene therapy?

Inserting a **working** copy of a gene into the cells that lack the ability to produce their own **protein**.

What is . The Human Genome Project?

The Human Genome Project was an international scientific research project with the goal of determining the base pairs that make up human DNA, and of identifying, mapping and sequencing all of the genes of the human genome from both a physical and a functional standpoint.

What is cloning?

Cloning involves make **exact** copies of an original organism.The clone will be genetically **identical**, but not necessarily **phenotypically** identical to the parent.

What is the law of segregation?

Each gamete receives one copy of each chromosome,  and therefore one copy of each gene, so one allele for each gene.

What are the autosomal ressive disorders?

**Sickle Cell Disease, Tay-Sachs Disease, Cystic Fibrosis:**

What is an autosomal dominant disorder?

Huntigtons disease

What are the x linked traits?

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* Hemophilia
* Muscular dystrophy
* Red/green colourblindness
* Early patterned baldness