Biology: 3B Inheritance (DNA and Genetics )

What is inheritance?

Inheritance is the transmission of genetic information from generation to generation

What is DNA and what does it make up?

a long molecule found inside the nucleus of cells. All of an organism’s DNA makes up its genome.

How is DNA structured?

supercoiled into chromosomes in order to fit in the nucleus.

It is a double helix with 4 bases.

What is RNA and its function?

a single-stranded molecule that carries genetic instructions for protein synthesis

Differences between DNA and RNA?

Structure

Function

DNA located in nucleus and mitochondria. RNA is found in the cytoplasm, nucleus, and ribosomes.

What are chromosomes?

thread-like structures of DNA, carrying genetic information in the form of genes

Where are chromosomes located?

The nucleus

What is a gene?

a short length of DNA found on a chromosome that codes for a specific protein

What can each chromosome be divided into?

Each chromosome can be further divided up into sections of DNA called genes.

What are alleles?

Versions of a gene. You have one copy from your mother and one from your father.

Alleles can be…

Dominant or recessive

What is a dominant gene mean?

A dominant gene (or allele) expresses its trait even when only one copy is inherited

What is a recessive gene mean?

A recessive gene only expresses its trait if both inherited alleles are the recessive type.

What does phenotype mean?

The phenotype is the actual characteristic expressed by the person’s genes.

What does genotype mean?

the combination of alleles that a person has that codes for their specific phenotype.

How do you write to present a dominant and a recessive allele?

The dominant allele always has a capital letter and you use the lower case version of the same letter to show the recessive allele.

What does homozygous mean?

having two identical alleles for a particular gene

What can you be homozygous for?

can be either homozygous dominant (both alleles are dominant, like BB) or homozygous recessive (both alleles are recessive, like bb

What is a monohybrid cross?

When you breed two organisms together and look at one trait

What is a punnet square?

genetic diagrams and predict the probability of certain phenotypes in the offspring.

What chromosomes are men and women?

Men have and X and a Y chromosome.

Women have two X chromosomes.

How does passing on the chromosomes for sex work when sperm meets the egg?

• All females are have two X chromosomes and can therefore only pass on an X in their eggs.

• Males have an X and a Y chromosome and therefore can pass on either X or Y in their sperm.

• Therefore depending on which sperm meets the egg, there is a 50/50 chance of having a boy or girl.

What are family pedigree charts?

special family tree diagrams showing genetic disorders.