It will depend partly on your uni and the syllabus that has been created by your lecturers.
I have only done Medical Genetics as a minor subject as a medical student, so the below may not help, but have a look.
A. TRADITIONAL CONCEPTS
1. Go through detailed DNA structure as the basis of genetics, and expand by looking at transcription factors, gene expression and repression.
2. mRNA, tRNA, rRNA and translation
3. Look at autosomal recessive and dominant transmission then sex-linked inheritance with examples.
4. Definitions of common terms e.g. homozygous, heterozygous, hemizygous, allele, heterochromatin, phenotype, genotype, exons, introns, euchromatin, HLA, karyotype, linkage, etc.
B. MODERN GENETICS
1. Gene therapy
2. Human Genome Project
3. Gene mapping
4. Genetic markers
5. sRNA, snRNA, snoRNA, siRNAs, miRNAs.
C. APPLICATION TO MEDICINE
1. Restriction endonuclease and splicing.
2. Disorders of metabolism e.g. phenylketonuria, albinism
3. Cancer genetics - alteration of cell regulatory systems, mutation, examples e.g. Philadelphia chromosome in CML
4. Immunogenetics - antigenic diversity, MHC, organ transplantation, Bruton's disease.
5. Genetic counselling
Hopefully, this should warm you up (it was -3 degrees C a few days ago ).
BEST OF LUCK - but bear in mind your uni's choices/your own lecture notes.